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Software development process

1. r Ls first_project Microsoft Visual Basic 2005 Express Edition BAX File Edit View Project Build Debug Data Tools Window Community Help MAERA at 4 Ga ak a Se DS 3 Fa ot Toolbox ix Form1 vb Design Start Page xX Solution Explorer ax All Windows F 2 1 i A Commen con ay H first project R Pointer S j My Project 2b Button ES Form1 vb v CheckBox rs 2 4 CheckedListBox ComboBox TA DateTimePicker A Label n A LinkLabel ListBox 222 ListView Solution Explorer g Data Sources MaskedTextBox Properties ix waa MonthCalendar Form1 System Windows Forms For v Tal NotifyIcon A Z 13 NumericUpDown nm o fay jowInTaskbar True 3 P al geese Size 427 301 ProgressBar mi SizeGripStyle Auto Error List vI amp StartPosition WindowsDefaultL 7 7 z a Tag 0 Errors t 0 Warnings i 0 Messages O o Erors D 7 Text My first Progra Description File Line Column Project TopMost False p7 Text The text assog ted with the control Ready e Change the caption of the form from Form 1 to My first program in VB by changing the text property in the properties window e Add the Enter your name label To do this double click the label icon from the toolbar A blank label should appear on your form All Windows F h Pointer ab Button CheckBox 2 9 CheckedListBox G2 ComboBox e Change its tex
2. Hello world Mid Hello world Mid string_in 5 4 Write a brief statement summarising the effect of the mid function 74 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Testing the Asc function Change string_out Mid string_in 1 1 into number_out Asc string_in and change Dim string_out as String to Dim number_out as Integer Run the program to test the Asc function Edit the coding of the String Function Tester program Like Len Asc is another function that takes a string as its input and returns a number so make the following changes You will also have to change the reference to string_out in the final line of code Record the results in a table like the one below adding a few tests of your own until you are sure you understand what Asc does Asc predefined function Input string Output number A olol lolo Write a brief statement summarising the effect of the Asc function SOFTWARE DEVELOPMENT INT 2 COMPUTING 75 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED hope you realised that the numbers produced by the Asc function are the ASCII codes for the characters you input As you should know from the C
3. Alter the coding like this You will also need to alter the labels on the form to prompt for a word rather than a letter and to enlarge the text boxes to hold a word uncoded_word txtln text length_of_word Len uncoded_word coded_word For counter 1 To length_of_word uncoded_char Mid uncoded_word counter 1 ascii_uncoded Asc uncoded_char ascii_coded ascii_uncoded 1 coded_char Chr ascii_coded If uncoded_char Z Then coded_char A If uncoded_char z Then coded_char a coded_word coded_word coded_char Next txtOut Text coded_word End Sub ew Stage 4 testing Devise some test data This should include e some normal data e some extreme data e some exceptional data Run the program using your test data and record the results in a table SOFTWARE DEVELOPMENT INT 2 COMPUTING 111 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS xy l 7 l A Stages 5 and 6 Documentation and evaluation As usual you should e print out hard copies of your form and the coding e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability 4 12 Do Loop Until We have used For Next loops to repeat a section of program a set number of times This is fine if we know how many
4. HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Next we design the list of steps pseudocode and then the coding for the command button Pseudocode Visual BASIC coding 1 Do the following 10 times Fori 0To9 1 1 prompt the user to enter a name Stored_name i InputBox Enter a 1 2 store the name in an array name 2 Next Next 3 Select a random number between Randomize 1 and 10 Number 4 Display the selected array TxtWinner Text element Stored_name number Variables required i and number both integers stored_name Q array of strings Stage 3 Implementation e Start a new Visual BASIC project e Create a form as above e Name the command button btnStart and the textbox txtWinner e Enter the code for btnStart declare the 2 variables and the array e Save the project and form in a new folder Stage 4 Testing Run the program to make sure it works correctly selecting a different winner every time To save time you can enter the names as Q W E R T etc from the top row of the keyboard SOFTWARE DEVELOPMENT INT 2 COMPUTING 143 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Lucky Prize Draw version 2 Program specification Design write and test a program which prompts the user to enter four names and four prizes The program should select a lucky winner at random and
5. Here is the list of steps pseudocode required Copy and complete the coding yourself Pseudocode 1 Set up variables to store the three numbers and the loop counter 2 Clear the list box 3 Store the multiplier entered by the user 4 Repeat the following from 1 to 12 4 1 Calculate the answer 4 2 Assemble the message 4 3 Display the message 5 Next Visual BASIC coding Ol Sie i ive meme Step answer counter multiplier MESSAQE Aeiyet tivses deere wuss Si reitet Items Add message Next Stage 3 Implementation e Start a new Visual BASIC project called Tables e Create a form as above e Give the command button list box and text box appropriate names e Enter the code for the command button e Save all 2 F A Stages 4 5 and 6 Testing documentation and evaluation Complete the testing documentation and evaluation of the program in the usual way 108 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 10 For Next tasks Choose one or more of the following program specifications and design implement and test a program to fulfil the specification Work through all the stages of the software development process from analysis to evaluation for your chosen task Remember A dragon in the dungeon eradicates mice Times tables advanced version
6. Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 2 Design a gt multiple greetings Joey We want the user interface to look like this It has a button a label and a list box Toolbox 1x All Windows F Common Con Pointer ab Button V CheckBox 2 4 CheckedListBox j ComboBox tl TA DateTimePicker A Label To create a list box click on this icon MaskedTextBox Next we design the list of steps pseudocode and then the coding for the button Pseudocode Visual BASIC coding 1 Do the following 25 times For Counter 1 to 25 2 Add the word Hello to the list box LstGreeti ems Add Hello Hello Hello Next Note It is usual to indent the code within the loop to improve readability Stage 3 Implementation e Start a new Visual BASIC project e Create a form as above e Name the button btnStart e Name the listbox IstGreeting e Enter the code for the button declare a variable Counter as Integer Make sure you save all SOFTWARE DEVELOPMENT INT 2 COMPUTING 99 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 4 Testing Run the program to make sure it works correctly There is no need for a table of testing for a simple program like this It is tricky to be sure that th
7. Programmer e two text boxes for output 22 12 03 Total cost 7 e one button Stage 2 Design pseudocode Here is a list of steps pseudocode to describe what this program has to do store the number of slabs wide store the number of slabs deep store the cost of one slab calculate the number of slabs required calculate the total cost display the number of slabs required display the total cost At the implementation stage we will turn each of these steps into VB code SO GIB QOD Stage 3 Implementation creating the form Start a new Visual BASIC project give it a suitable name and create a form to match the one above e Set the caption text property of the form to be Belinda s Slab Calculator e Add the six labels e Add five text boxes and position them on the form e Name the textboxes from top to bottom txtWide txtDeep txtCost txtTotalNumber txtTotalCost e Add a button and position it on the form e Change the name of the button to btnCalculate e Change the text on the button to Calculate slabs and cost If you can t remember how to do these look back to pages 41 to 42 Before going any further make sure you have saved your work e SOFTWARE DEVELOPMENT INT 2 COMPUTING 55 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 3 Implementation coding Don t w
8. BEG oe ry Now that your program is complete write e auser guide e a technical guide Stage 6 Evaluation Pre cw Write a brief evaluation of the program e Is it fit for purpose e Does it have a good user interface e ls the code readable 70 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 12 Predefined string functions In Section 3 10 we looked at the predefined functions Int Cint Round Sqrt and Sin These functions are all designed to work with numbers There are also some useful predefined functions for manipulating strings We are going to examine UCase LCase Len Mid Asc and Chr Make anew function tester v program similar to the one 3 String Function Tester aax you used in Section 3 10 Enter a string e Start a new project calling it String Function Tester e Create a form like this e Enter the following code for the Apply Function button Result by A Programmer Clear Apply 18 10 07 Function Add code for the clear button as you did in Section 3 7 Bam Private Sub btnFunction_Click di Dim string_in As String Dim string_out As String string_in txtEnter Text string_out UCase string_in txtResult Text string _out O End Sub SOFTWARE DEVELOPMENT INT 2 COMPUTING 71 Learning and Teaching Scotla
9. e Prompt the user to enter their type of membership in a club Membership codes are J for Junior for Intermediate and S for Senior e Prompt the user to enter Yes or No The program should accept YES Yes yes NO No or no e Prompt the user to enter a name The program should only accept a name beginning with the letter A Hint Use Mid e Prompt the user to enter a password which can include letters and numbers The program should only accept a password that is at least 6 characters long Hint Use Len SOFTWARE DEVELOPMENT INT 2 COMPUTING 133 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS 5 3 Other standard algorithms There are many other standard algorithms used by programmers For this unit you need to e beable to recognise and code the standard algorithm for input validation e know about four other standard algorithms and understand where and when they might be used You don t need to be able to code these other standard algorithms unless you study the Higher Software Development unit The other standard algorithms you need to know about are e finding a minimum e finding a maximum e counting occurrences e linear search All of these algorithms apply to a list of data items stored in a computer system These could be lists of names or lists of numbers student marks for exam
10. 36 49 64 81 100 Hint These are all numbers squared 7 2 4 8 16 32 64 128 256 512 1024 2048 Hint These are powers of 2 Example 4 9 2 General Purpose Counting Program Stage 1 Analysis Program specification Data flow diagram copy and complete Design write and test a program to display any list of numbers given the starting number lower limit the final DER number upper limit and the step size Stage 2 Design arte General counting program Sketch a user interface something like this lower limit It should have a command button labels upper limit three text boxes for input and a list box C for the output 104 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS A list of steps pseudocode is shown below Copy and complete the coding yourself Pseudocode Visual BASIC coding 1 Set up variables to store the three Dim numbers and the loop counter Dim Dim Dim 2 Clear the list box EE ltems Clear 3 Store the lower limit entered by lower txt Text the user 4 Store the upper limit entered by Upper ssedecceout terns the user 5 Store the step size entered by the Stepsize user 6 Repeat the following starting at 20 see geen Ko haere ay Step lower limit and going up to upper limit in st
11. 4 15 6 4 0 4 0 100 5 1 56 5 299 5 0 020 6 28 3 6 929 6 0 111 7 23 8 7 922 7 0 001 8 2 38 8 99 8 0 002 9 15 6 9 99 9 0 200 10 99 3 10 299 10 0 120 What value would each of the following standard algorithms return numbers in brackets refer to columns 2 and 3 find minimum find maximum count occurrence of 15 6 99 0 001 linear search for 2 38 929 0 111 Which standard algorithm would be used by the national census organisation to cD find out how many people called Mary live in the UK find out the oldest person living in the UK discover whether or not there was an individual called Stan D Ard al Gorithm in the UK O 136 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS 5 4 Using arrays All of the standard algorithms which you met in the last section operate on a list of data items In this section we will see how a computer program can store a list of items Suppose a program was required which would prompt the user to enter and store the names and test marks for three students Let s try Stage 1 Analysis data flow diagram three names e three sets of test gt Stage 2 Design We want the user interface to look like this It has a single command button and a title We will use input boxes to enter the
12. A primary school teacher wants a program which will allow a pupil to type in any whole number The program will then display the relevant times table up to a maximum multiplier set by the pupil The display should be in the format 5 times 1 equals 5 5 times 2 equals 10 5 times 3 equals 15 and so on Cost and weight calculator A greengrocer needs a program which will allow him to type in the price i of 1 kg of any item The program should then display the cost of 1 0 1 0 2 up to 1 8 1 9 2 0 kg of the item gt y The output might look something like this NV 0 kg costs 0 0 1 kg costs 0 20 0 2 kg costs 0 40 0 3 kg costs 0 60 and so on Cubic numbers A mathematician wants a list of cubic numbers 1 8 27 64 125 starting and finishing at any point on the list The results should be displayed like this 2 cubed 8 3 cubed 27 4 cubed 64 and so on SOFTWARE DEVELOPMENT INT 2 COMPUTING 109 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Quadratic function calculator A pupil has been asked to draw a graph of the function y 3x 4 She needs a table of the values of the function between 5 and 5 She is not sure about the step size between points so wants the program to allow her to choose any step size The results should be displayed like this X 1 gt gt gt gt gt gt gt gt y 7 X 2 gt gt gt gt
13. and write pseudocode instructions and draw a structure diagram for each one Don t make it too complicated In the tea example broke making tea into five steps You could have broken it into many more detailed steps For example getting a mug out of the cupboard could be broken down into smaller steps walk across to the cupboard open the door choose a mug lift it out close the door walk back across the room Try to break the task down into between four and eight steps We will use pseudocode in Section 3 when we start to develop our own computer programs There are other graphical methods of representing the structure of a program These include structure charts and flowcharts Some use a variety of boxes to represent different types of instruction For example you might see to represent a repeated action to represent a choice to represent a step which will be broken down into smaller steps SOFTWARE DEVELOPMENT INT 2 COMPUTING 17 Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS 1 6 Implementation In software development implementation is the process of converting a program design into a suitable programming language There are thousands of different programming languages out there all with their own advantages and disadvantages For the purposes of this course you only need to know about two main groups machine code and high level languages Y
14. hidden spaces in the input text box as this will affect your results Len predefined function Input string Output string Comment Hello world HELLO WORLD 123 One Two Three 28 A Write a brief statement summarising the effect of the Len function SOFTWARE DEVELOPMENT INT 2 COMPUTING 73 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Note The Len function takes a string input and returns a numeric output so really we should make a further change to the program Dim string _out as String should be changed to Dim number_out as Integer with other references to string_out also changed to number_oult Testing the Mid function Edit the coding of the String Function Tester program Change string_out Len string_in into string_out Mid string_in 1 1 Run the program to test the Mid function This time you will need to edit the Mid line of code each time you run the program Record the results in a table like the one below adding a few tests of your own until you are sure you understand how Mid works Mid predefined function Input string Coding used Output string Comment Hello world Mid string_in 1 1 Hello world Mid string_in 2 1 string_in 3 1 Hello world Mid string_in 1 2 Hello world Mid string_in 1 3
15. trigonometric functions sine cosine and tangent If you complete this unit then continue to Higher Software Development you will also learn to create your own functions so that you are not limited to the predefined ones provided by Visual BASIC If you want to experiment with the trigonometric functions the code you need is result System Math Sin number 3 141 28 180 to get the Sine of a number in degrees result System Math Cos number 3 14128 180 to get the Cosine of a number result System Math Tan number 3 14128 180 to get the Tangent of number Your table of testing might look like this Input Expected output Actual output Comment 0 0 90 1 180 0 30 0 5 Important Make sure you save this function tester program as you will use it again later in the course SOFTWARE DEVELOPMENT INT 2 COMPUTING 65 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 11 Working with words and numbers example The next example program uses all three data types integer single and string The problem A basketball team manager wants a program which will input a player s name squad number and points scored in the first three games of the season It should then calculate the player s average score to the nearest whole number and display a summary of the player s details Stage 1 Analysis p
16. 55 Macro Macro recorded 07 01 2804 You should be able to recognise the actions you Keyboard Shortcut Ctrl Shiftt k took Range Ai Select 7 x With electing Font For example the first section Name arial records the macro s name Size 18 and shortcut key Strikethrough alse Superscript False Subscript False Next comes the action of OutlineFont False selecting cell Al changing Shadow False the font to18 point making it Underline xlUnderlineStyleNoe bold and so on ColorIndex xlautomatic End With Selection Font Bold True Range A3 D13 Select Range D13 Activate The macro is actually coded in a scripting language called Visual BASIC for Applications or VBA for short What use is a macro e Keep course 2 xls open e Open course_copy xls e Hold down Ctrl Shift K The file course_copy xls should be automatically formatted by the macro to be the same as course2 xls If the user had several similar unformatted spreadsheets and wanted them all formatted in this way he could save a great deal of time by using the macro A macro is a time saving program written in a scripting language which can be activated by a series of key strokes for repeated use A macro cannot exist alone it only works with an application program in this case Excel In this example we have seen a macro being used with a spreadsheet Macros can be used with many other application packag
17. 7 Dim question as Integer This new variable here is the loop counter for the For Next loop Here is the For Next loop to Randomize repeat the next section six times For question 1 To 6 first Int Rnd 10 1 second Int Rnd 10 1 counter 0 correct_answer first second This adds the Question number as a title for the Input Box Do user_answer InputBox What is amp first amp amp second amp Question amp question counter counter 1 If user_answer lt gt correct_answer Then MsgBox Wrong try again Loop Until user_answer correct_answer MsgBox Well done You took amp counter amp tries Next End Sub You now have a loop within a loop The technical term for this is nested loops e Make the above changes to the coding e Alter the form to call this version 4 e Save the revised form and project Carry out some thorough testing of your program using normal extreme and exceptional data 120 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Now export your program as a template so that you can keep the original and create a new final version based on the template Modify the program so that it e asks multiplication questions rather than addition e uses random numbers between 1 and 12 e asks five q
18. A gt B BoC Hello gt Ifmmp Visual BASIC gt Wjtvom CBTJD and so on Let s create a simple program to generate this type of code It only works for single letters In Section 4 11 you will see how to code whole words or even sentences Stage 1 Analysis program specification Design write and test a program to take any character in the alphabet and code it using the system A B etc Stage 1 Analysis data flow diagram coded letter any letter Stage 2 Design user interface Simple character coding program We will use a simple design with text boxes for both the input and output letters a code command button and a clear command button Enter a character code Coded character by A Programmer 19 10 07 SOFTWARE DEVELOPMENT INT 2 COMPUTING 79 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 2 Design pseudocode The program must carry out the following steps enter and store the input character convert it to an ASCII code add 1 to the code convert it back to a character display the character OV gt ISS Stage 3 Implementation e Start a new project called AB_code e Create a form like the one above e Name the text boxes txtIn and txtOut e Name the buttons btnCode and btnClear The variables needed will be A string variable to hold the input cha
19. Alison Alison Bill Albert alison Cliff Bill end Doris Bert END Sarah Ahmed Comment You should have noticed three problems with the program e it doesn t count names which start with a lower case a e it doesn t stop when you enter end in lower case e it adds the word END to the list You should be able to modify your code to solve these problems Hints e Use the function UCase in step 3 4 e Make step 3 2 conditional If name lt gt END e Make the end of loop condition into a complex condition using OR FAY St 5and6 D tati S valia A ages 9 an ocumentation and evaluation As usual you should e print out hard copies of your form and the coding e save your program and tidy up the files into a folder e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability SOFTWARE DEVELOPMENT INT 2 COMPUTING 123 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Example 4 15 2 Password protection Design write and test a program for a bank cash machine The program should prompt the user to enter their PIN If the PIN is correct it should display Welcome to the VB Bank message 1 If not it should notify the user that their PIN was entered wrongly message 2 and let them try again but only allow three tries I
20. Print it Saving your program e Choose Save all from the File menu to save any changes you have made SOFTWARE DEVELOPMENT INT 2 COMPUTING 45 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED When you exit you may be first_project cog prompted to save changes to He Edt yew Favorites Toda ey w both the project file and the form O E sets a ile Ds file Click Yes to both of these FleandroiderTasis in CF trom Other Places emia Visual BASIC will have created arr s Ai e E several files to store your project first project Va Fom Designer vb a which will be found in a single Bele a folder Do not delete any of VES Vile source fie these ew User guide User guide Start the program by double Write a couple of sentences describing clicking ow the first_project icon how to use your program Click ow the start icon on the merw bar Enter your name in the text box Click the button A message should appear IYN Technical 3 Technical guide QA g Hardware used Write a note of the types of hardware and Compaq Presario 2100 laptop software you have used Operating Systemi MS Windows XP Software used Visual BASIC 2005 EE 46 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 6 Evaluation
21. Q2 Macros are written in scripting languages like VBA Q3 They allow automation of frequently repeated complicated combinations of actions Q4 For automating a complex set of formatting commands in a word processor or automating a complex query in a database 148 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 ANSWERS TO QUESTIONS After Section 3 1 Q1 A command button a text box a label Q2 This icon starts the execution of a program Q3 Clicking on a command button is a common VB event After Section 3 12 Q1 Description Predefined function Returns the ASCII code of a character Selects a group of characters out of a string Turns any character into upper Lcase case Takes an ACII code and returns Ucase the character it represents Changes any character into lower ia case Counts the number of characters Mid Asc l Chr in a string Q2 Mid sentence 1 1 W Mid sentence 1 4 What Mid sentence 9 2 25 Mid sentence 19 1 Q3 any letter ASCII code gt ASCII code character string no of characters SOFTWARE DEVELOPMENT INT 2 COMPUTING 149 Learning and Teaching Scotland 2009 ANSWERS TO QUESTIONS Section 4 9 a For counter 3 To 36 Step 3 b For counter 0 To 99 Step 9 c For counter 10 To 0 Step 1 d For counter 0 To 4 5 Step 0 75 e For counter 50
22. Section 3 High level programming getting started 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 3 10 3 11 Introducing Visual BASIC Input and output example Input and output tasks Other forms of output Declaring variables Working with numbers example Adding a Clear button Arithmetical expressions Working with numbers tasks Predefined numeric functions Working with words and numbers example 10 13 15 16 18 18 18 19 20 22 22 25 26 26 27 29 35 38 48 49 51 53 60 61 62 63 66 SOFTWARE DEVELOPMENT INT 2 COMPUTING 3 Learning and Teaching Scotland 2009 CONTENTS 3 12 3 13 Predefined string functions Example program using Chr and Asc 71 79 Section 4 High level language programming basic constructs 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 4 12 4 13 4 14 4 15 4 16 Making choices If Then Else Multiple Ifs Using AND example Using And task Complex conditions Repetition Repetition using For Next Counting using For Next For Next tasks Using loops to work with strings Do Loop Until Random numbers Arithmetic tester More examples using Do Loop Until Other forms of conditional loop Section 5 High level language programming standard algorithms 5 1 Input validation 5 2 Input validation tasks 5 3 Other standard algorithms 5 4 Using arrays 55 Examples using arrays
23. Task 2 a Work through the stages of the software development process following the example on the previous pages as a model b The data flow diagram will look something like this incomplete Name Message including name and age Age a c You will need two text boxes on your form one for each of the inputs and each with a different name d You will need two variables to store the two items of data so your code will begin something like this Private Sub btnMessage_Click Dim name As String Dim age As String Note Age is a number so we should really store itas a number rather than as a string but it doesn t matter here because we are not going to do any calculations with it name txtName Text age txtAge Text 48 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 4 Other forms of output In the Welcome to VB program the output message appeared in a message box The line of code to do this was MsgBox welcome to VB amp name It is also possible to make the output message appear either e directly on the form in a label or e ina text box on the form Output to a label Two changes are needed to the program Firstly add a label on the form and name it IbIMessage Secondly change the line of code from MsgBox welcome to VB amp name to IbIMes
24. check if over 75 Design implement and test a program to solve the problem given above SOFTWARE DEVELOPMENT INT 2 COMPUTING 95 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 6 Complex conditions In Section 4 4 we used a conditional statement with an AND in it If percent gt 60 And percent lt 70 Then grade B This is an example of a complex condition Complex conditions use a combination of the terms AND OR and NOT in logical combinations Here are some examples If age gt 60 And gender F Then pension true If country UK Or country USA Then language English If temp lt 12 And heat T Or heat X Then turn_heating_on If Not password correct_password Then MsgBox Try again If age lt 5 Or Age gt 85 Then eligible No If Not age gt 5 And age lt 85 Then eligible No If Not txtInput Text Y Then MsgBox Are you sure If Ans Too Or Ans Two Or Ans To Then Correct True Note These two examples are equivalent to each other Programming Task Colour changer Design write and test a program which asks the user to enter a letter and turns the form red if R or D is entered green if Gor N is entered blue if B or E is entered yellow if Y or W is entered black if C A or K is entered T
25. correct answer 7 Display message You took counter tries to get that right Gio hes The code for this is counter counter 1 Turn the pseudocode into Visual BASIC and adapt your program accordingly Edit the changes into your program and check that it works Improvement 3 The third improvement would be if the program could be made to ask a different question each time instead of always asking 2 2 To do this we need to use VB s random number generator 114 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 13 Random numbers Visual BASIC provides the programmer with a predefined function Rnd to generate random numbers Before we use it in the Arithmetic Tester program we will use a simple program with a For Next loop to learn how the Rnd function operates Enter the following coding for the Set up a form like this command bunor w random numbers Of x Private Sub btnStart_Click generates lists of random number Dim number as Single Dim counter As Integer by A Programmer 02 01 04 IstRandoms tems Clear For counter 1 To 10 number Rnd e Name the command button IstRandoms Items Add number btnStart Next e Name the list box IstRandoms End Sub Run this program Write down the list of 10 random numbers produced The Rnd function produces random
26. gt gt gt gt y 16 X 3 gt gt gt gt gt gt gt gt y 31 andsoon 4 11 Using loops to work with strings So far we have only used the loop counter variable to display numbers However it can be used to do other things too Example 4 11 1 Adapting the AB_coder program to code whole words Version 2 of the AB_coder program from Section 4 3 can code single characters We can use a For Next loop to adapt the program to code whole words instead of single characters Here is how it works in pseudocode Prompt the user to enter a word Check how many characters there are in the word Create a new empty coded word Repeat the following for each letter in the word 4 1 1 extract the letter from the word 4 1 2 code it 4 1 3 add it on to the new coded word Next letter 6 Display coded word Fe I o 110 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS and here is the code Private Sub btnCode_Click adapted coding for the Code button by A Programmer on 19 10 07 Make a copy of the AB_code_v2 project and call it AB_code_v3 Dim uncoded_char coded_char As String Dim uncoded_word As String Dim length_of_word As Integer Dim coded_word As Siring Dim ascii_uncoded ascii_coded As Integer Dim counter As Integer check how to do this on page 90
27. in any process Pseudocode is read from top to bottom a structure diagram is read from left to right A user guide tells you the features of the software how to use it and possibly a tutorial The technical guide gives information on installation and the technical specification of the computer required to run the program Normal extreme and exceptional testing A game could have bugs fixed or new features added SOFTWARE DEVELOPMENT INT 2 COMPUTING 147 Learning and Teaching Scotland 2009 ANSWERS TO QUESTIONS After Section 2 1 Q1 Q2 Q3 Q4 Q5 Q6 High level is easier to understand High level is easier to correct Machine code and assembler are low level languages Pascal and BASIC are two high level languages there are many more High level languages are designed to be understood by humans LLLs are designed to be understood by computers High level languages are more readable easier to fix bugs designed for problem solving After Section 2 4 Q1 Q2 Q3 Q4 Interpreters and compilers A compiler translates a whole program before executing it An interpreter translates line by line Compiled programs run more quickly because they are already in machine code so don t need to be translated After Section 2 6 Q1 Amacro is a program to automate a process in an application it can be activated by a combination of keys whenever it is needed
28. is easier to spot and correct errors SOFTWARE DEVELOPMENT INT 2 COMPUTING 23 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Here is a simple program written in a number of high and low level languages 10 Number 1 20 Answer Number 1 30 PRINT Answer 40 END The first three are all examples of high level languages BASIC Logo and Pascal All use words that are understandable to humans make number 1 make answer number 1 sav answer This is a low level language called LDA 1 PROGRAM adder fee 6502 assembler STA 1000 VAR answer number real not so easy to LDA 1000 BEGIN understand ADC STA 1001 JSR OSWRCH Number 1 Answer number 1 WRITELN answer This final one is 6502 machine code which is completely unintelligible to most humans 10101001 00000001 10000101 01110000 10100101 01110000 In fact all five of these programs do more or less the same job think you will agree that high level languages are much more practical for writing programs than machine code 01101001 00000001 10000101 01110001 00100000 11101110 24 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Questions Which type of language high or low level is easier to understand Which type would be easiest to correct if it had
29. less than or equal to equal to lt gt not equal to 4 2 If Then Else Example 1 Credit limit The problem When you try to take money out of an ATM automatic teller machine commonly called a hole in the wall you are only allowed to withdraw cash up to your credit limit For example if your credit limit is 100 and you try to withdraw 50 then it should work fine However if you try to withdraw 150 you will not be allowed to and a message will appear on the screen advising you that this is over your credit limit Stage 1 Analysis program specification Design write and test a program to e take a number entered by the user e compare it with a credit limit 100 e report over the credit limit if the number is over 100 Stage 1 Analysis data flow diagram over credit limit message on screen if appropriate any number SOFTWARE DEVELOPMENT INT 2 COMPUTING 83 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 2 Design user interface ATM credit limit check The user interface will use a text box for data entry with two buttons and use a message ah men do you box for the response wish to withdraw Stage 2 Design pseudocode Click to confirm by A Programmer 19 10 07 There are only two steps for the OK command button When it is clicked
30. number Next End Sub For example to produce e random numbers between 1 and 20 change it to number Int Rnd 20 1 e random numbers between 51 and 60 change it to number Int Rnd 10 51 e random even numbers between 0 and 10 change it to number 2 Int Rnd 6 116 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Try experimenting with this line until you understand how it works Sometimes it take a little thought to work out exactly what numbers to put in so that you get the right range and don t miss out the highest or lowest number Test your program with the following lines of code In each case make a note of the results and explain what you get Line of code Results Explanation number Int Rnd a number Int Rnd 20 number eae i n 2000 number 2 Int Rnd 50 1 number 2 Int Rnd 8 1 Tasks e Modify your program so that when you click on the button it produces a single dice roll a random number between 1 and 6 Hint You won t need a For Next loop e Modify your program so that it produces a double dice roll and displays the number on each dice and the total score Hint You will need to generate two random numbers every time you click the button SOFTWARE DEVELOPMENT INT 2 COMPUTI
31. numbers between 0 and 1 To produce random whole numbers between 1 and 10 we need to do three things to the line number Rnd e First we need to multiply by 10 to produce a random fraction between 0 and 10 e Then we need to chop off the fraction part using the function Int see Section 3 10 e Finally we need to add 1 otherwise the highest number will always be 9 as it is rounded down by the Int function Change the line number Rnd into number Int Rnd 10 1 SOFTWARE DEVELOPMENT INT 2 COMPUTING 115 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Now run the program again Write down the list of random numbers This time they should all be whole numbers between 1 and 10 Stop the program Then run the program again And again You will notice that it always generates the same list of random numbers To make them really random you need to add the keyword Randomize at the start of the program anywhere before the keyword Rnd The coding for your random number generator should now look like this Private Sub btnStart_Click generates lists of random number Dim number as Single Dim counter As Integer Randomize IstRandoms tems Clear You can adapt this line ina variety of ways to produce other sets of random numbers For counter 1 To 10 number Int Rnd 10 1 IstRandoms Items Add
32. of the Chr function SOFTWARE DEVELOPMENT INT 2 COMPUTING 77 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Questions 1 Match these predefined functions to their descriptions one has been done for you Description Predefined function Returns the ASCII code of a character eon Selects a group of characters out Asc of a string Turns any character into upper nate case Takes an ACII code and returns Ucase the character it represents Changes any character into lower rae case Counts the number of characters Chr in a string 2 If sentence What is 25 times 8 what would be the output from a Mid sentence 1 1 b Mid sentence 1 4 c Mid sentence 9 2 d Mid sentence 19 1 3 Which predefined functions are represented by these data flow diagrams ASCII code any letter ASCII code character string No of characters 78 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 13 Example program using Chr and Asc Using these two predefined functions you can manipulate strings in all sorts of interesting ways Maybe when you were younger you tried communicating with your friends using codes The simplest code is the one which replaces each letter with the following letter from the alphabet so
33. on an older one 90 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 4 Using AND example Example Exam Mark Grader The problem A program is required that can be used to assign grades to exam marks automatically Over 70 is an A over 60 is a B over 50 is a C over 45 is a D and less than 45 is a fail Stage 1 Analysis program specification Design write and test a program to e prompt the user to enter the highest possible score for an exam e g 80 e prompt the user to enter a student s name first name an surname e prompt the user to enter the student s mark e g 63 e calculate the percentage mark e display a message giving the student s initials percentage and grade Stage 1 Analysis data flow diagram exam out of message on screen including student name percentage mark student name student mark es Stage 2 Design user interface The user interface will use text Eyam Mark Grader boxes for data entry with two command buttons and use a Enter possible score message box for the response Enter student s first name Enter student s surname J K clear Click to confirm by A Programmer 19 10 07 Enter students score SOFTWARE DEVELOPMENT INT 2 COMPUTING 91 Learning and Teaching Scotland 2009 HIGH LE
34. program we developed in Section 3 13 for coding letters using the A gt B code When you tested it you should have discovered that it works well for every letter except Z The problem is that if you add one to the ASCII code for Z you get the ASCII code for a bracket symbol We can correct this by using two conditional statements to cover the two special cases upper case and lower case Z Private Sub btnCode_Click adapted coding for the Code button version 2 py A Programmer on 19 10 07 Dim uncoded_char coded_char As String e Load the program AB_code Dim ascii_uncoded ascii_coded As Integer e Select Export Template from the File menu e Choose Project Template as the project type e Click Finish to save your AB_code project as a template uncoded_char txtIn text ascii_uncoded Asc uncoded_char ascii_coded ascii_uncoded 1 e Select New Project from the File menu coded_char Chr ascii_coded e Instead of Windows Application select the template you have just created special case for Z and z e Name the new project AB_codev2 If uncoded_char Z Then coded_char A e Alter the coding as shown changes in If uncoded_char z Then coded_char a bold e Run the program carefully testing that it txtOut text coded_char handles Z and z correctly End Sub e Save all changes Note Follow the steps above carefully whenever you want to create a new program based
35. programmer 15 09 07 It s a good idea at this stage to save your work by selecting Save all from the File menu It will be saved using the name you gave it when you started Save Project Name first_project Location C My Documents Visual Studio 2005 Projects v Solution Name first_project Create directory for solution Now you can try to run your program e Todo this either choose start from the run menu or just click on the m start icon on the menu bar pee Note VB uses a built in interpreter to translate your program into machine code line by line as it executes the program Some versions of VB also have a compiler which lets you convert completed VB programs into stand alone executable files 42 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED The form should appear with a cursor in the text box Nothing happens That s because we have only created the form We need to write program code for what is to happen when someone clicks the command button an event e Click on the end icon to return to th _ editing environment SH f Stage 3 Implementation coding e Enter your name and click the command button We need to implement Formi vb Start Page Form1 vb Design x the coding for the button binMessage v Click v E Public Cla
36. student_ student_ namel N name 1 nameal name 3 name 4 Similarly Dim mark 4 as Integer sets up an array that can store five integers pe A A A A 140 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS The really useful thing about an array is that the program can refer to the whole array at once or to any single element Now let s see how using arrays lets us simplify the program we have been working on Here is the version that doesn t work adapted for five students Private Sub btnDataEntry_Click Dim student_name As String Dim mark As Integer Dim i as Integer Fori 1to5 student_name InputBox Enter a name mark InputBox and their mark Next Fori 1to5 IstOutput ltems Add student_name IstOutput ltems Add mark Next End Sub and here is a version that does work using arrays Private Sub btnDataEntry_Click Dim student_name 4 As String Dim mark 4 As Integer Dim i as Integer Fori 0to4 student_name i InputBox Enter a name mark i InputBox and their mark Next Fori 0to4 IstOutput ltems Add student_name i IstOutput ltems Add mark i Next End Sub box The first time through the loop i 0 so the first name and mark are stored in array elements student_name 0 and mark 0 Next time
37. the menus commands and options are supposed to do Could it be improved in any way The third aspect of evaluation that we will consider is readability This is of no direct concern to the user of the software but is important for any programmer who may need to understand how the program works It is to do with the way that the coding has been implemented Is it possible for the program code to be read and understood by another programmer perhaps at a later date when the program is being updated in some way In Section 3 we will see some techniques for improving the readability of a program SOFTWARE DEVELOPMENT INT 2 COMPUTING 19 Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS 1 10 Maintenance This final phase happens after the program has been put into use There are different types of maintenance that might be required These are called corrective maintenance perfective maintenance and adaptive maintenance You don t need to know these names until Higher level but it is useful to think about what they mean Corrective maintenance means fixing any bugs that appear once the program is in use Of course these should all have been discovered during testing However most programs but not the ones you will be writing are so huge and complex that some bugs are bound to slip through unnoticed If the bugs are serious in nature the software company might issue a free patch on its
38. the original PIN program but use it to begin the new program Select Export Template from the File menu Choose Project Template as the template type Leave all the default settings on the next page and click Finish VB will save the PIN program as a template Select New Project from the File menu Instead of Windows Application select the template you have just created Give the new project a name e g Password_program and continue as normal 126 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 16 Other forms of conditional loop There are four variations of conditional loop in Visual BASIC So far we have only used the Do Loop Until form of loop In some high level languages this is the only kind of conditional loop and it is possible to manage without the other kinds However for completeness here is a brief summary of all four Type of loop Syntax Comments Do Always executed at least Line s of code to be once as condition is Do Loop Until tested at the end stops repeated a z when the condition Loop Until condition becomes true Do amall Conaion Only executed if the i Line s of code to be ee ate Do Until Loop condition is true as it is repeated ence tested at the beginning Loop Do Loops while the l Line s of code to be condition is true and Poa EROP ANIG repeated Sto
39. website so that users can download the patch and install it with the software so fixing the bug If it is a minor bug they may not bother Perfective maintenance is adding new features to the software These might be suggested as a result of the evaluation stage or they might be suggested by users These new features will then be added to the software and re issued as a new version That s why software often has version numbers Each version results from corrective and perfective maintenance of the earlier versions So for example BloggProg 3 2 will be similar to BloggProg 3 1 but with bugs fixed and some new features added The third type of maintenance is adaptive maintenance This is where the software has to be changed to take account of new conditions The most obvious example is when a new operating system comes out Perhaps BloggProg 3 2 was designed to run under Windows 2000 When Windows XP came along changes had to be made to BloggProg so that it would work under the new operating system 20 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS Questions 1 Match up these descriptions of the stages of the software development process with the correct names one has been done for you Stage Evaluation Testing Implementation Design Documentation Analysis Maintenance Description Writing a user guide and technical gui
40. what the program should do Finally run the program using your chosen test data and compare the actual results with the expected results If they agree all is well If not you may need to go back and de bug the program Table of testing for Belinda s slab calculator Inputs Expected outputs Actual outputs Comment Cost Total Total Total Wide Deep of Total cost number number cost slab 4 5 2 00 20 40 00 N orma o 20 199 200 398 00 data 4 5 5 9 2 99 20 59 80 10000 9000 2 00 90000000 180000000 Exirem 0 an an 0 0 e data y y 5 4 2 50 20 50 00 58 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Activity SiGe Add some other examples of normal and extreme data to the I A table then test the program to make sure it handles them all correctly Finally run some exceptional data tests and note the results either in the table or as notes below it Summarise your testing The program carries out all calculations according to the specification when supplied with sensible data However the program does give results when supplied with negative data without generating an error message Also the program does not display the total cost in the standard format e g 59 80 is displayed as 59 8 Stage 5 Documentation Print the form image and c
41. 1 store the number entered by the user 2 if itis over 100 display the warning message There is only one variable required a numeric variable to store the amount entered by the user As this could be something like 23 50 it needs to be a single rather than an integer Stage 3 Implementation e Start a new project called ATM e Create a form as shown above e Name the text box txtInput e Name the buttons btnOK and btnClear e Enter the coding for the OK command button as shown below Private Sub btnOK_Click coding for the OK command button warns the user if the amount is over the credit limit 100 written by A Programmer on 19 10 07 Dim Number as Single Number txtInput Text If Number gt 100 Then MsgBox Number amp is over your credit limit End Sub e Enter the coding for the Clear button as usual 84 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS ewe Stage 4 Testing gt Devise some test data This should include e some normal data for example 20 clearly under the limit 120 clearly over the limit e some extreme data for example 99 99 just under the limit 100 00 exactly on the limit 100 01 just over the limit e some exceptional data for example 5 a negative number 999999 9999 a ridiculously large number A a letter when a number is ex
42. Answers to questions 82 83 86 91 95 96 97 98 101 109 110 112 115 118 121 127 129 133 134 137 142 146 4 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 INTRODUCTION Introduction Tutor guide This teaching and learning material is designed to cover all of the content needed by a learner to pass the Software Development unit of Intermediate 2 Computing However it is the responsibility of the tutor to check the content coverage against the SQA unit specification The pack covers the knowledge and understanding required for Outcome 1 assessment and the practical skills required for Outcome 2 There are many opportunities throughout the unit especially in Sections 3 4 and 5 for students to demonstrate the practical skills required and generate the required evidence For unit assessment use should be made of the NAB assessment materials provided by SQA multiple choice test and practical skills checklist Note that learners completing this unit as part of the Intermediate 2 Computing course should be given opportunities to develop the higher order problem solving skills required for the external course assessments examination and practical coursework tasks This can be done by providing past exam paper questions and further programming tasks such as the specimen coursework task provided by SQA The pack has not been designed for a student to use uns
43. Do Loop Until make use of the loop counter within a loop create nested loops a loop within a loop create and use a Project Template Check all the items on this list If you are not sure look back through this section to remind yourself When you are sure you understand all of these items you are ready to move on to Section 5 128 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Section 5 High level language programming standard algorithms 5 1 Input validation There is a saying in computing which goes Garbage in garbage out or just GIGO You have probably heard stories about people who have received a gas bill for 1 000 000 or similar Usually the company will blame this on a computer error However computers very rarely make mistakes More often the problem is that the computer has been fed with the wrong data to start with If you feed in wrong data then the answer that comes out of the system will be wrong too wrong data in wrong answer out A well designed program should prevent or at least reduce the likelihood of wrong data being entered into a system For example there was a program in Section 4 4 which took in a student s exam mark and worked out their grade Suppose a student scored 59 so should have been given a B but the teacher was in a hurry and the m
44. ELOPMENT INT 2 COMPUTING 13 Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS Check your answers below You should have the following Stage Description 1 Analysis B Deciding what type of game you want to create and what features you want it to have F Working out the details of what the screens will look 2 Design like what menus and functions there will be and other detailed aspects of the program 3 Implementation D Actually writing all the program code 4 Testing G Getting users to try out the program to make sure it works under most conditions BS DCRmGniatian A Writing a user guide and technical guide for the software E Checking that the program does what it is supposed 6 Evaluation to do is easy to use and can be fixed if there is a problem C Adapting the game to run on a different type of 7 Maintenance computer 14 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS In this course especially in Section 3 onward you will be putting this software development process into practice when you produce some simple programs in a high level computer programming language For the moment it is worth trying to learn the steps in the correct order usually use a silly mnemonic for this like A Dragon In The Dungeon Eradicates Mice Impleme
45. FORTRAN was designed for carrying out mathematical and scientific calculations Prolog is good for developing programs in artificial intelligence COBOL is for developing commercial data processing programs Activity ee Make a list of six or so programming languages you can find y A J these in textbooks or on websites For each one write down LAN where it gets its name from and what it is good for Here are some examples to get you started Name Source of name Used for Ada After Countess Lovelace US military systems Logo Greek for thought Education FORTRAN FORmula TRANslation Early scientific language All these languages are what we call high level languages That is to distinguish them from low level languages What do we mean 2 2 High and low level languages Inside every computer there is a processor This is a chip containing digital electronic circuits These circuits work with tiny pulses of electricity and electronic components The pulses of electricity can be represented by the digits 1 and 0 Every item of data and every instruction for the processor is represented by a group of these binary digits Processors only understand these binary digits The only inputs you can make to a processor are groups of binary digits The only output that a processor can make is a group of binary digits 22 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Sco
46. Hardware is the items of equipment that make up a computer system Q2 Examples of software include any application packages e g Microsoft Word any operating system e g Windows 97 or any document or file Q3 Item Hardware Software monitor y database y Windows 97 scanner y an email Internet Explorer y mouse y modem y a computer game y a word processor digital camera y 146 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 ANSWERS TO QUESTIONS After Section 1 10 Q1 Q2 Q3 Q4 Q5 Q6 Stage Description Evaluation Writing a user guide and technical guide for the software Testing Working out the details of what the screens will look like what menus and functions there will be and other detailed aspects of the program Implementation Deciding what type of game you want to create and what features you want it to have Design Actually writing all the program code Documentation Adapting the game to run on a different type of computer Analysis Checking that the program does what it is supposed to do is easy to use and can be fixed if there is a problem Maintenance Getting users to try out the program to make sure it works under most conditions The three criteria used to evaluate software in this unit are fitness for purpose user interface and readability Both show the main steps
47. NATIONAL QUALIFICATIONS CURRICULUM SUPPORT Computing Software Development using VB2005 2008 EE INTERMEDIATE 2 The Scottish Qualifications Authority regularly reviews the arrangements for National Qualifications Users of all NQ support materials whether published by Learning and Teaching Scotland or others are reminded that it is their responsibility to check that the support materials correspond to the requirements of the current arrangements Acknowledgement Learning and Teaching Scotland gratefully acknowledges this contribution to the National Qualifications support programme for Computing Learning and Teaching Scotland 2009 This resource may be reproduced in whole or in part for educational purposes by educational establishments in Scotland provided that no profit accrues at any stage 2 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 Contents Introduction Tutor guide Student guide Section 1 Software development process 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 Software The development process A dragon in the dungeon eradicates mice Analysis Design Implementation Testing Documentation Evaluation Maintenance Section 2 Languages and environments 2 1 2 2 2 3 2 4 2 5 2 6 2 7 Computer languages High and low level languages Translators Interpreters Compilers Text editors Scripting languages and macros
48. NG 117 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 14 Arithmetic tester We can now combine what we have learned Arithmetic tester Joe about random numbers with our arithmetic tester program from Section 4 12 Here is the current version of the form and coding for the command button by A Programmer 13 03 09 Arithmetic tester v 2 Coding for command button Private Sub btnQuestion_Click generates a question to the user and waits for the correct answer Dim user_answer As Integer Dim correct_answer As Integer Dim counter as Integer Make sure you have added the extra counter 0 lines of code here correct_answer 4 Do user_answer InputBox What is 2 2 counter counter 1 If user_answer lt gt correct_answer Then MsgBox Wrong try again Loop Until user_answer correct_answer MsgBox Well done You took amp counter amp tries End Sub 118 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS e Change the label on the form to read version 3 e Modify the coding as below changes in bold Private Sub btnQuestion_Click generates a random question to the user and waits for the correct answer The variables first and second
49. ONMENT 2 4 Interpreters Option 1 is to go to the conference yourself and deliver your speech in English one sentence at a time After each sentence a professional translator who can understand English and also speaks fluent Japanese will turn your sentence into Japanese This will continue right through your lecture with the interpreter translating each sentence as you go along Computer interpreter programs work in the same way The interpreter takes each line of high level language code translates it into machine code and passes it to the processor to carry out that instruction It works its way through the high level language program one line at a time in this way This works fine but it has a couple of important AALY disadvantages Think about the analogy again Your 1 a J f KL hour lecture will take 2 hours to deliver as each od ME ney sentence is spoken by you in English then by the ee interpreter in Japanese The other disadvantage is that if you are then asked to deliver your lecture again in iJ another Japanese city you will need to have it translated all over again as you are delivering it the second time The same problem is true of computer interpreters The process of translating the high level language program slows down the running of the program Secondly the high level language program needs to be translated every time it is used This is a waste of computer resources and means that the user must al
50. Scotland 2009 SOFTWARE DEVELOPMENT PROCESS 1 3 A dragon in the dungeon eradicates mice Exactly the same process goes into the production of a piece of software The software engineers and their colleagues carry out all the stages of the software development process in order analysis design implementation testing documentation evaluation maintenance BENS e Activit IK Activity Consider the production of a new game program by a software company Here are descriptions of the seven stages but they are in the wrong order Copy and complete another table like the one above and slot the stages into the correct places A Writing a user guide and technical guide for the software B Deciding what type of game you want to create and what features you want it to have C Adapting the game to run on a different type of computer D Actually writing all the program code E Checking that the program does what it is supposed to do is easy to use and can be fixed if there is a problem F Working out the details of what the screens will look like what menus and functions there will be and other detailed aspects of the program G Getting users to try out the program to make sure it works under most conditions Stage description 1 Analysis Design Implementation Testing Evaluation 2 3 4 5 Documentation 6 7 Maintenance SOFTWARE DEV
51. Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS containing all the instructions about how to work the new TV and probably a technical manual for repair engineers Stage 6 Evaluation Once the model is in production the company will want to evaluate the new product Does it do what it is supposed to do Is it easy to use And from the engineer s point of view is it easy to repair Stage 7 Maintenance Stage 6 should be the end of the story but in the real world there needs to be Stage 7 Maintenance There are different kinds of maintenance fixing faults that turn up once it is being used regularly improving the design to make it even better or making changes for other situations like making a version that will work in another country These seven stages are required for the production process TAN ee Ok let s see if you have got the idea Choose any type of manufactured object it could be a car an item of clothing a ready made meal a toy a piece of furniture a building etc N Now copy and complete this table writing one sentence to describe each of the seven stages in the production of your chosen object Object chosen Stage Description 1 Analysis 2 Design 3 Implementation 4 Testing 5 Documentation 6 Evaluation 7 Maintenance 12 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching
52. The evaluation of your program should answer the following questions e ls the program fit for purpose Does it do what is required by the specification e ls the user interface good to use Could it be improved e ls the program coding readable so that another programmer could understand how it works Your answers might look like this Evaluation The program fulfils the specification If yow enter a name it responds with aw appropriate message The user interface ix easy to use it prompty for input and the command button iy clearly labelled The coding hay comment lines and wey sensible variable names to make it readable Stage 7 Maintenance Maintenance might involve making the change suggested above or adapting the program to run on a different type of computer system You don t need to do either of these for Intermediate 2 SOFTWARE DEVELOPMENT INT 2 COMPUTING 47 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 3 Input and output tasks Task 1 A similar program Develop a similar program to the one you have already written to output a personalised Happy Birthday message Obtain hard copies of the form and code for your new program Develop a new program which asks the user to enter their name and age and displays a message saying something like Bryan how does it feel to be 17 years old Hints for
53. To 50 Step 10 f For counter 1 To 10 with counter 2 g For counter 1 To 11 with 2 counter Section 5 3 Q1 Column 1 Column 2 Column 3 Finding minimum 1 56 922 0 001 Finding 99 3 999 0 200 maximum Count 15 6 3 99 1 0 001 2 occurrences Linear search 2 38 8 929 6 0 111 6 Q2 a Count occurrences b Finding maximum or minimum if searching dates of birth c Linear search 150 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009
54. UTING 63 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Testing the INT function Input Expected output Actual output Comment 2 5 9 999 9 001 5 5 9 001 Testing the CINT function Edit the coding of the program to change result Int number into result Cint number Run the program again and complete a similar table of testing to the one above Can you summarise the difference between INT and CINT Testing the ROUND function Edit the coding of the program to change Run the program again and complete a similar table of testing to the one above Experiment with different numbers instead of 2 Summarise how this function works Testing the SQRT function Edit the coding of the program to change result Cint number into result System Math Sqrt number Run the program again and complete a similar table of testing to the one above What happens when you enter a negative number Can you explain this result CInt number into result System Math Round number 2 What happens when you enter a number like 0 000000001 What does this mean 64 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Other predefined functions Visual BASIC provides many other predefined functions including the
55. VEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Example 4 9 3 Multiplication tables Stage 1 Analysis Program specification Data flow diagram copy and complete Design write and test a program to display any multiplication table chosen by the user in the form 1 x 5 5 2x5 10andso on as far as 12 x 5 60 Stage 2 Design Sketch a user interface something like Multiplication tables Which table do you want this It should have a button labels a text box for inputting the user s choice of table and a list box to display the output Each line that appears in the 1 X 5 5 10 list box should the look like this t the piliplier 4h Hi ee made up of symbol X chosen by symbol a five parts 1 2 3 ee multiplier To do this we need several variables e the counter an integer e the multiplier an integer supplied by the user e the answer an integer calculated by the program e astring variable which we ll call message which links together the five parts shown above and stores them as a single message to be displayed in each line of the list box The line of code to assemble this message will look like message counter amp x amp multiplier amp amp answer SOFTWARE DEVELOPMENT INT 2 COMPUTING 107 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS
56. VEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 2 Design pseudocode There are several steps for the OK button When it is clicked ORO OE ee store the possible score for the exam store the student s first name store the student s surname store the student s mark calculate the percentage mark calculate the grade extract the initial letter from the first name extract the initial letter from the surname display an appropriate message box showing initials percentage and grade The program will use several variables It is useful to write them down as a table Variable name Variable type Used to store Max_mark Integer What the exam is out of e g 80 First_name String Student s first name e g Albert Surname String Student s surname e g Einstein Mark Integer Student s actual mark e g 63 Percent Single Student s percentage e g 53 7 Grade String Student s grade e g D Init1 String Student s first initial e g A Init2 String Student s second initial e g E Converting these into variable declarations and the pseudocode into VB code we should get the following code for the OK button First the initial comment lines and variable declarations Private Sub btnOK_Click code for the OK button by A Programmer 19 10 07 variable declarations Dim max_mark As Integer Dim first_name surname As String Dim mark As Int
57. You should keep a folio of evidence this should include documentation of all the stages of the software development process You will see the following icons throughout these notes Computer based practical task you will need access to a computer with Visual BASIC 2005 EE or similar installed for this task Questions for you to answer you can check your own answers against the sample answers given at the end of this pack LE Activity not computer based this will usually require some SN A written work You should ask your teacher or lecturer to check your work whenever you complete a computer based practical task or a non computer based activity SOFTWARE DEVELOPMENT INT 2 COMPUTING 7 Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS Section 1 Software development process 1 1 Software This unit is about software What is software You should already know that any computer system is made up of hardware and software The term hardware is fairly easy to understand because you can see it It is all the pieces of equipment that make up the system the processor monitor keyboard mouse printer scanner and so on Software is not so obvious It is all the programs instructions and data that allow the hardware to do something useful and interesting Think about all the different items of software that you have used in the last week or so Here is the li
58. a mistake in it Name two low level languages Name two high level languages Explain the main differences between high and low level languages Write down two advantages of high level languages O3 COn ee It looks like high level languages have all the advantages compared to machine code However there is one major problem processors don t understand high level languages at all To get round this problem computer scientists have developed translator programs which can translate high level languages written by humans into machine code understood by processors High level language Machine Translator code program 2 3 Translators There are two main types of translator program that you need to know something about These are called interpreters and compilers To understand the difference it is useful to think about an analogy from the non computer world Imagine that you were the world expert in some obscure subject like the anatomy of the microscopic tube worms of the steppes of Knazakstan You have been invited to present a lecture on this subject at a conference to be held in Japan Most of the delegates at the conference do not speak or understand English and you do not know any Japanese How are you going to communicate There are two options that you can take SOFTWARE DEVELOPMENT INT 2 COMPUTING 25 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIR
59. a new Visual BASIC project Create a form as above Name the button btnDataEntry Enter the code for the button declaring all required variables Save the project and form in a new folder Stage 4 Testing Test the program with some normal test data You might well be thinking that this is a very tedious example and that there should be an easier way of implementing the program You are right You should be thinking Loop This is an ideal situation to employ a For Next loop as the same action has to be repeated three times ee lt 2 138 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Here is simpler version using two For Next loops Private Sub btnDataEntry_Click Dim student_name As String Dim mark As Integer Dim i as Integer Fori 1to3 Student_name InputBox Enter a name mark InputBox and their mark Next Note we can t call the variable name as name is a VB object property so we use student_name instead Fori 1to3 IstOutput ltems Add student_name IstOutput ltems Add mark Next End Sub Implement and test this new version There is a problem The program has only stored the last name and mark we entered Each name and mark has been stored in the same variable each time over
60. age 1 Analysis Program specification Design write and test a program to display 1 2 3 4 5 99 100 Stage 2 Design We want the user interface to look like this It has a command button a label and a list box called IstNumbers Here is the list of steps pseudocode and then the coding for the button Pseudocode 1 Clear the list box 2 Do the following 100 times 3 Display the counter in the list box example of fixed loops This times the action is executed is programmer using the value Later we will see that it is possible to construct loops where the number of times the action is executed is NOT known in advance WDA 0 1 Oy TE Data flow diagram 1 2 3 99 100 on the screen Counting program click to start by A Programmer Visual BASIC coding LstNumbers Items Clear For counter 1 to 100 LstNumbers Items Add counter Next Instead of message being displayed in the list box the current value of counter is displayed instead 102 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 3 Implementation e Start a new Visual BASIC project called Counter e Create a form as above e Name the command button btnStart e Name the listbox IstNumbers e Enter the code for the button declare a variable Count
61. ar we are going to make it pop up in a separate message box Stage 2 Design pseudocode Pseudocode is just a fancy name for a list of steps that the program should carry out every time you run it You write it in a sort of cross between English and computer language It lets you think about the steps carefully without getting bogged down in the actual coding Another advantage of pseudocode is that it can then be easily converted into almost any high level language you want in our case Visual BASIC Here is a list of steps for our program pseudocode e Store the name e Display the message That s it That is all our program is supposed to do 40 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 3 Implementation creating a form Now we are ready to start coding Start up Visual BASIC on your computer Choose File New Project and select Windows Application Name it first_project Your screen should now display the VB environment New Project Templates Visual Studio installed templates AS amp 2 Windows Class Library Console My Movie Screen Saver Application Application Collecti Starter Kit My Templates Search Online Templates A project for creating an application with a Windows user interface Name first_project
62. ark was entered as 599 by mistake The computer doesn t have any common sense so it processes the data it is given and awards the student an A Garbage in garbage out You could prevent this sort of error by making it impossible to enter a mark of over 100 We would describe a mark of over 100 as being invalid Invalid data is data which couldn t possibly be correct or which doesn t make sense in the context To prevent the input of invalid data we can put the coding for input of data inside a conditional loop which only proceeds if the data entered is valid A SOFTWARE DEVELOPMENT INT 2 COMPUTING 129 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS conditional If statement can also be inserted to warn the user if invalid data is entered In VB it could look like this Do mark InputBox Enter a mark up to 100 If mark gt 100 then MsgBox Too high Loop Until mark lt 100 e Create a form like the one shown here le ay o e Name the textbox txtValidMark amx e Enter the code above for the button click click to event enter a i mark e Add a variable declaration for the variable mark e Add the line txtValidMark Text mark to Student mark display the valid mark in the text box on the form Run the program to test that it prevents the user from entering an inva
63. arn T f3 how to deal with these in Section 4 3 Congratulations You have completed Section 3 Here is a summary of what you should be able to do using VB D VA 4 lt design and create a form e add text boxes buttons labels and captions e add code for a button e change the properties of an object e analyse a problem using a data flow diagram e write pseudocode and convert it into VB code e declare string integer and single real variables e use text boxes for both input and output e use message boxes for output e use input boxes for input e write VB code for simple calculations e testa program using normal extreme and exceptional data e use Int Cint Round Sqrt and Sin predefined functions e use Ucase Lcase Len Mid Asc and Chr predefined functions e write brief user guides and technical guides for simple programs e evaluate a program in terms of fitness for purpose user interface and readability Check all the items on this list If you are not sure look back through this section to remind yourself When you are sure you understand all of these items you are ready to move on to Section 4 SOFTWARE DEVELOPMENT INT 2 COMPUTING 81 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Section 4 High level language programming basic constructs 4 1 Making choices So far all the programs you have written follow the same list
64. assign them a prize chosen at random The program should then display the name of the winner and the chosen prize Work through all the stages of the software development process for this program analysis design implementation testing documentation and evaluation 144 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Congratulations You have completed Section 5 Here is a Summary of what you should now be able to do using VB Sy lt e everything from the Section 3 checklist e everything from the Section 4 checklist e write the pseudocode for the input validation standard algorithm e write VB coding for a standard input validation algorithm e use complex conditions using Or and And for input validation e declare arrays e use For Next loops to handle arrays You have now completed the whole unit on software development By working your way through all the example programs and tasks in this package you should have demonstrated all the practical skills required to pass the unit and have enough evidence to support this You should also now be ready to sit the multiple choice NAB for this unit Good luck SOFTWARE DEVELOPMENT INT 2 COMPUTING 145 Learning and Teaching Scotland 2009 ANSWERS TO QUESTIONS Answers to questions Section 1 1 Q1
65. core rounded to the nearest whole number 9 Ol Go Nes Stage 3 Implementation creating a form e Create a new form matching your design e Name the text boxes txtDetails and txtAverage e Name the button btnStart a3 Basketball Team manager ee x Player details Average score by A programmer 1810 07 SOFTWARE DEVELOPMENT INT 2 COMPUTING 67 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 3 Implementation coding the start button First think about the variables that will be needed to store the six items of data e players_name will be a string variable e g Belinda McSporran e squad_number will be an integer as it will be a whole number e g 73 e game_1 game_2 and game_3 will be integers e g 3 2 and 0 e average will be a single as it might not be a whole number e g 1 667 e Now double click on the button to open a code window Declare all of these variable using Dim statements Private Sub btnStart_Click code for the start command button by A Programmer on 18 10 07 Dim players_name As String Dim squad_number As Integer Dim game_1 game_2 game_3 As Integer Dim average As Single For the next section of code translate each line of pseudocode into Visual BASIC The only new syntax is that for an input box players_name InputBox Enter the player s name squad_numbe
66. d Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 5 Declaring variables The programs in Sections 3 2 and 3 3 were designed to process words like your name or address The program in Task 2 also handled a phone number but it treated this as a string of characters Dim phone as String If a program has to process numbers then we have to tell the computer to expect a number rather than a string The reason for this as you probably know from the Computer Systems unit is that computers store different types of data in different ways It is good programming practice to consider all the data that will need to be stored while the program is running We do this at the design stage A data flow diagram is a useful tool for doing this although it only tells us the data that goes in and out of the program There may also be other data which needs to be stored during the processing between input and output We will consider three types of data in this course computing 29 5 Par cw Activity 5 7 A Einstein P TD7 5700 Look at these items of data Can you group them E into three basic types Monaco 0 006 You might have grouped them into these three lists List 1 120 699 100 5700 9999 List2 computing book A Einstein TD7 Monaco List3 29 5 5 7 0 006 List 1 are all whole numbers We call them integers and so does VB List 2 are all groups of characters We call them strings a
67. d other code in black 44 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 FUE HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 4 Testing The next stage is to make sure the program works Pree eae E e As before click on the start icon on the menu bar e Enter your name in the text box e Click on the button first_project Ed A message box should pop up with the appropriate message in it If not click on the end icon go back to the coding and check it carefully Correct any errors Run it again Welcome to VB Albert Einstein If it does work well done Would you buy a piece of software that had only been tested once Probably not One test is not enough We need to test the program systematically So run some more tests some normal tests like the one above but also try some more extreme testing For example what happens if you enter a number instead of a name or if you click the button before entering a name Stage 5 Documentation Firstly you might want some hard copy evidence of your program it s your first VB program so you may feel justifiably proud of it Printing your program Select Print from the File menu to obtain a hard copy of your coding If you want a hardcopy of your form e Run your program e Hold down the lt alt gt lt prtsc gt keys e Paste into an application e
68. data and the output will appear in a listbox names and marks displayed on form Names and marks Click to enter data Next we design the list of steps pseudocode and then the coding for the button Pseudocode Visual BASIC coding 1 Enter and store the first student s name first_name InputBox Enter 1 name 2 Enter and store the first student s mark first_mark InputBox and their mark 3 Enter and store the second student s name second_name InputBox Enter next name 4 Enter and store the second student s mark second_mark InputBox and their mark 5 Enter and store the third student s name 6 Enter and store the third student s mark and soon 11 Display the first student s name IstOutput Items Add first_name 12 Display the first student s mark IstOutput Items Add first_mark 13 Display the second student s name 14 Display the second student s mark and so on 15 Display the third student s name 16 Display the third student s mark SOFTWARE DEVELOPMENT INT 2 COMPUTING 137 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS The variables required are e first name second_name third_name all stings e first mark second_mark third_mark all integers Stage 3 Implementation Start
69. de for the software Working out the details of what the screens will look like what menus and functions there will be and other detailed aspects of the program Deciding what type of game you want to create and what features you want it to have Actually writing all the program code Adapting the game to run on a different type of computer Checking that the program does what it is supposed to do is easy to use and can be fixed if there is a problem Getting users to try out the program to make sure it works under most conditions 2 What three criteria will be used for evaluating software in this unit 3 What is the relationship between pseudocode and a structure diagram 4 Name two items of documentation usually provided with a software package and describe what you would expect each one to contain 5 What three types of testing should be applied to any software 6 Describe two examples of maintenance that could be required on a game program SOFTWARE DEVELOPMENT INT 2 COMPUTING 21 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Section 2 Languages and environments 2 1 Computer languages Just as there are many human languages there are many computer programming languages that can be used to develop software Some are named after people like Ada and Pascal Some are abbreviations like PL 1 and Prolog All have different strengths and weaknesses
70. e column headings e Make them bold The spreadsheet should now look like this Sy course2_xls Orienteering Course 1 Control identifier terrain distance m H gate in wall 150 2 A corner of track 200 a B in woods 120 4 J stream crossing 165 5 Us top of slope 210 6 P bend in path 240 7 C hollow 120 8 F top of hill 175 g W junction of fences 200 10 K end of house 185 e Click on stop recording Save the improved spreadsheet as course2 xls All the series of actions that you applied to course xls to turn it into course2 xls have been recorded and stored as a macro 30 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT To see the macro you have created e Goto the Tools menu e Select Macro e Select Macros A dialog box like the one shown below should appear with your named macro listed under the name you gave it Cancel Step Into Create EERE Delete Macros in Jal Open Workbooks Options Description Macro recorded 07 01 2004 e Click on Edit SOFTWARE DEVELOPMENT INT 2 COMPUTING 31 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Another window will open which displays the code of the macro you have recorded like this course2_xls Modulel Code oO x General hd tidy_up_ss X Sub tidy_up_S5S tidy up
71. e program first 94 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Extra task 1 Upper case initials If you entered a student s name as e g albert einstein the initials would be displayed as ae It would be better if they were changed automatically to AE A simple change in the coding of the OK button is required Hint You will need to use the Ucase predefined function Extra task 2 A grade A new grade called A has been introduced for marks of 80 and over Change the coding to reflect this new grade Remember to change the condition for an A as well as introducing a new condition for A Pav A Stages 5 and 6 Documentation and evaluation As usual you should e print out hard copies of your form and the coding e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability 4 5 Using And task Example Can I drive The problem A program is required that asks the user to enter their age then displays one of the following messages as appropriate e Sorry you can t drive if you are under 16 e You can only drive a moped if you are 16 e You can only drive a car or moped if you are 17 20 e You can drive any vehicle if you are 21 74 e You need a medical
72. e program has actually printed the message 25 times so alter the line of code to include the counter like this IstGreeting ltems Add counter amp Hello then try running it again Modifications 1 Alter the coding so that it displays the messages e Goodbye 12 times e must work harder 200 times e This is very easy 100 times Modifications 2 The program would be much more useful if it was possible to make changes to the message and the number of times it was displayed without having to alter the coding each time This can be achieved by using variables Change the coding as follows A string variable called message will store the message and an integer variable called how_many will store the number of repetitions Private Sub btnStart_Click improved For Next example Dim counter As Integer Dim message As String Dim how_many As Integer An InputBox is like a Message Box but is used to get input from the user and store it in a variable message InputBox Message required how_many InputBox How many repetitions This command clears the list box IstGreeting ltems Clear Instead of a fixed number here the loop will continue up to the number stored in how_many For counter 1 To how_many IstGreeting Items Add counter amp amp message Next End Sub Whatever string is stored in the variable called message will be displa
73. e the actual value of the data they store can vary or change during the running of a program It is important to make sure that all variables are correctly declared the right type integer string or single and with sensible readable variable names Variables can have almost any name but each variable name e must begin with a letter e must not be a VB keyword like End or Print or MsgBox e must not contain spaces no_of_pupils is OK but no of pupils is not Note There are several other types of variable but we will only use these three in this unit 3 6 Working with numbers example The programs in Section 3 3 were designed to process words like your name or address In this section we will develop programs to process numbers both integers and real numbers singles The first example is called Belinda s Slab Calculator Belinda works in a garden centre selling paving stones Customers come in with the plans for their patio and ask how many slabs they will need and how much it will cost For example Mr Mclinally says his back garden is Here is the problem 35 slabs wide and 16 slabs deep He wants the pink granite slabs at 2 99 each How many slabs will he need and what will they cost The first step is to be absolutely clear about what the program must do This must be agreed between the customer Belinda and the programmer before starting The agreed definition of what the program mus
74. e to create stand alone applications However small programs called macros can be developed within some existing application packages Example Creating an Excel spreadsheet macro e Set up a small spreadsheet like the one shown below Save it as course xls e Save asecond copy of the same spreadsheet as course_copy xls E course xls 1 Orienteering Course 1 2 3 Control identifier terrain distance m 4 1H gate in wall 150 5 2A corner of track 200 6 3B in woods 120 7 4J stream crossing 185 8 5 T top of slope 210 9 6P bend in path 240 10 C hollow 120 11 8 F top of hill 175 gW junction of fences 200 13 10K end of house 185 14 e From the Tools menu select Macro then Record New Macro The following dialog box should appear Record Macro 2 xi Macro name tidy_up_ss Shortcut key Store macro in Ctrl shirt k This Workbook 7 Description recorded 07 01 2004 OK Cancel SOFTWARE DEVELOPMENT INT 2 COMPUTING 29 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT e Enter the name tidy_up_SS e Enter the shortcut key Ctrl Shift K e Then click OK Warning Follow these instructions very carefully all your actions are being recorded e Select cell a1 the title of the spreadsheet e Change its font to 18pt Bold e Select A3 to D13 all the data e Centre it all using the centre button on the menu bar e Select row 3 th
75. eger Dim percent As Single Dim grade As String Dim init1 init2 As String 92 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Next storing the user inputs from the text boxes into variables pseudocode steps 1 to 4 Store user inputs Note use of a comment line to max_mark txtMax Text indicate the purpose of the code first_name txtName Text surname txtSurname Text mark txtMark Text Next the calculation of the percentage mark pseudocode step 5 calculate percentage mark percent mark max_mark 100 Step 6 is the calculation of the grade from the percentage using a series of If statements The statements for grades A and Fail are straightforward For grades B C and D complex conditions are required using And calculate grade If percent gt 70 Then grade A If percent gt 60 And percent lt 70 Then grade B If percent gt 50 And percent lt 60 Then grade C If percent gt 45 And percent lt 50 Then grade D If percent lt 45 Then grade Fail Steps 7 and 8 use Mid to extract the first character of the first name and surname extract initials from name init Mid first_name 1 1 init2 Mid surname 1 1 Finally step 9 uses a message box to display the results This is a little bit complicated e init init2 percent a
76. ell as the program displaying the prize that has been won we want the colour of the form to change We will use the following colours red 1 blue 2 green 3 yellow 4 black 5 All we need to do is change the coding so that each If statement has two actions to be performed displaying the appropriate message and changing the form colour This is how the code should look now Modify the Lucky Number program and check to see that it correctly changes the form colour Note Me BackColor refers to the background colour property of the current Form One further change that is useful is to make the Clear button turn the form back to its standard grey colour as well as clearing the text box The coding for this is Private Sub btnClear_Click txtNumber Text Me BackColor Color Gainsboro End Sub Note Gainsboro is the name for the default light grey colour Usually a conditional statement is of the format If condition Then action Private Sub btnOK_Click coding for the OK command button displays an appropriate message for each number and changes the form colour written by A Programmer on 19 10 07 Dim Number As Integer Number txtNumber Text If Number 1 Then Me BackColor Color Red MsgBox Number amp wins you a colour TV End If If Number 2 Then Me BackColor Color Blue MsgBox Number amp wins you a mobile phone End If If Numbe
77. eps of stepsize 7 Display the counter heen eee Items Add e Start anew Visual BASIC project called GPCounter e Create a form as above e Give the button list box and text boxes appropriate names e Enter the code for the button e Save all SOFTWARE DEVELOPMENT INT 2 COMPUTING 105 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 4 Testing Carry out systematic testing of the program completing a table like the one shown below Inputs Expected Actual outputs Comment outputs Lower Upper Step limit limit size 10 20 3 10 13 16 19 Normal 1000 1250 daa 1000 8000 2500 1500 1750 10 0 2 10 8 6 4 2 0 Devise your own test data covering a range of normal extreme and exceptional data Write a short summary of your testing If all the tests results were as expected move on to stages 5 and 6 If not go back and correct your coding until it works correctly ay DEX ry Stages 5 and 6 Documentation and evaluation As usual you should e print out hard copies of your form and the coding e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability 106 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LE
78. er as integer Stage 4 Testing Run the program to make sure it works correctly it should produce a list of numbers from 1 to 100 in the list box There is no need for a table of testing for a simple program like this You are going to use this program as a template to experiment with For Next loops In each case below e Replace the line of code For counter 1 To 100 with the modification suggested e Run the program e Note the results in a table like this Coding used Results For counter 1 To 100 1234 99 100 Modifications For counter 1 To 9999 For counter 1 To 100 Step 2 For counter 2 To 100 Step 2 For counter 0 To 100 Step 10 For counter 10 To 10 Step 5 For counter 100 To 1 Step 5 For counter 0 To 5 Step 0 5 The final modification will require a change to another line of coding Can you work out what it will be Hint 0 5 is not an integer Soe Pe NS SOFTWARE DEVELOPMENT INT 2 COMPUTING 103 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Questions Write the Visual BASIC coding of a For Next loop to produce each of the following lists of numbers 1 3 6 9 12 15 18 33 36 2 0 9 18 27 99 3 10 9 8 7 6 5 4 3 2 1 0 4 0 0 75 1 5 2 25 3 3 75 4 5 5 50 40 30 20 10 0 10 20 30 40 50 6 1 4 9 16 25
79. es 32 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Example 2 Creating a word processing macro e Open any word processing document e As before from the Tools menu select Macro then Record New Macro e Name the macro bold_red_text e Assign a shortcut key combination perhaps Ctrl Alt R e Click OK Now the macro is being recorded e Select bold and text colour red from the menu bar e Click to stop the macro recording Now you can use the macro e Select any block of text e Activate the macro by using the shortcut key combination You can also activate the macro by selecting it from Tools Macro Macros This macro would be useful if you have several documents to work through in each of which you have been asked to change the main heading to bold red text If you needed to change all the sub headings to italic blue text you could set up a similar macro to do that Alternatively you could edit the macro directly by changing the VBA code in the edit window Try editing the above macro to make it produce blue italic text The examples above are very simple ones Macros can be used to automate any task within an application program For example they can be used to activate long and complex data manipulations within a database application or specialised formatting within any type of document Some applications such as AppleW
80. et Here is a reminder of these important steps making sure you know what the program has to do deciding on the form layout the inputs outputs and processes required creating the form and writing the code for any actions Implementation making sure the program works correctly writing a user guide and a technical guide reviewing how well the program solves the original problem making any upgrades required SOFTWARE DEVELOPMENT INT 2 COMPUTING 37 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Questions 1 Name three types of object that could be found on a VB form 2 What does this icon do gt 3 Give an example of a VB event 3 2 Input and output example Almost every program that has ever been written follows a pattern called IPO This stands for inout process output Most programs are designed to take in some data to process it in some way then to give out some data Example 1 To keep things simple for your first VB program we are going to develop one which misses out the middle step It will simply take in some information and give it out again It s not very useful but it will teach you some of the basics of VB programming We start with the program specification Design implement and test a program which will prompt the user to enter his or her name The program should then display the
81. f the user enters their PIN wrongly three times they should be warned that their card is being kept message 3 Stage 1 Analysis data flow diagram PIN entered at keyboard Appropriate message Stage 2 Design We want the user interface to look like this VB Bank It has a command button a title and a text Click to rT box for messages to appear The user will be enter PIN prompted to enter their PIN through an input box First we design the list of steps pseudocode and then the coding for the command button We will use a Do Loop Until as the number of attempts the user makes is unknown in advance by the programmer The condition to end the loop will be that the PIN is correct OR that the user has had three attempts 124 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Pseudocode Visual BASIC coding 1 Set a counter equal to zero counter 0 2 Store correct PIN correct_pin 1347 3 Do the following Do 3 1 prompt the user to enter their pin InputBox Enter your PIN PIN 3 2 if PIN is correct display If pin correct_pin then txtMessage Text message 1 Else display Welcome to VB Bank else message 2 txtMessage Text PIN entered wrongly try again 3 3 add 1 to the counter counter counter 1 4 Until the PIN is correct o
82. g to type these notes e Windows XP on another laptop e Windows 2000 on a computer at school e MacOS 8 1 on my trusty old Mac clone e MacOS X 2 on my iMac Thirdly a full list would include all the actual documents files web pages emails and so on that had accessed as these are also software That would be too long a list so I ll ignore it here Yl How about you Make a list of all the software programs and VY VJ operating systems that you have used over the last few days The point about all these programs is this they didn t grow on trees They are available for us to use because they have been designed and created by teams of software developers In this unit we are going to learn about the process of developing software and to apply this process to develop some simple programs of our own 1 What is the meaning of the term hardware 2 Give three examples of software SOFTWARE DEVELOPMENT INT 2 COMPUTING 9 Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS 3 Identify each of the following as either hardware or software Item Hardware Software Monitor v Database Windows 97 Scanner An email Internet Explorer Mouse Modem Computer game Word processor Digital camera 1 2 The development process Before we think about how software is developed it is worth considering how any p
83. he design while others will develop the electronics to go inside Each part will be tested on its own then the whole thing will be assembled into a hopefully working TV set Stage 4 Testing Before the new model can be put on sale it will be thoroughly tested A wide range of tests will be carried out It might be tested under normal conditions It could be put in a room at normal room temperature and checked to see that all the controls work correctly the display is clear it is nice and stable and so on If it passes this type of testing it might next be tested under extreme conditions For example does it still work if the temperature is below freezing or very hot and humid if it used for long periods of time or with the volume or the brightness or contrast set to their maximum values Finally it could be tested under exceptional circumstances What happens if a 2 year old picks up the remote and presses all the buttons at once What happens if there is a power cut or a power surge If it fails any of these tests it might be necessary to go back to the implementation or even design stage and do some further work before re testing If it passes all the testing then it can go into production Stage 5 Documentation However the development isn t yet complete Some documentation will be needed to go with the TV A user manual SOFTWARE DEVELOPMENT INT 2 COMPUTING 11 Learning and
84. he program should respond to both upper case and lower case inputs 96 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 7 Repetition So far every program you have written starts at the beginning executes each line once then stops at the end If you want to repeat the program you have to click on the start icon to run it again It is often useful in a program to be able to repeat a line or group of lines automatically To do this you can use a FOR NEXT loop Here is a simple example program that would benefit E simple loop demo from a FOR NEXT loop e Create a form like this with a single button called btnLoop e Add a listbox you will find this in the tool bx just below label and name it IstMessage e Enter this coding Private Sub btnLoop_Click code to display 10 greetings on the screen by a not very good programmer who hasn t been taught about FOR NEXT loops Note This is the letter I not the number 1 IstMessage ltems Add Have a nice day IstMessage ltems Add Have a nice day IstMessage ltems Add Have a nice day IstMessage ltems Add Have a nice dav IstMessage ltems Add Have a nice day IstMessage ltems Add Have a nice day IstMessage ltems Add Have a nice day Is
85. he user interface will use a text box for data entry with two buttons and use a message Enter a number fy box for the response between 1 and 5 Stage 2 Design pseudocode Click to confirm by A Programmer 19 10 07 Here are the steps for the OK command button When it is clicked store the number entered by the user if the number is 1 display You have won a colour TV if the number is 2 display You have won a mobile phone and so on BO MS There is only one variable required a numeric variable to store the number entered by the user As this must be 1 2 3 4 or 5 it should be declared as an Integer 86 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Stage 3 Implementation e Start a new project called Winner e Create a form as shown above e Name the text box txtNumber e Name the buttons btnOK and btnClear Enter the coding for the OK command button as below Private Sub btnOK_Click coding for the OK command button displays an appropriate message for each possible number written by A Programmer on 19 10 07 Dim Num as Integer Num txtNumber Text If Num 1 Then MsgBox Num amp wins you a colour TV If Num 2 Then MsgBox Num amp wins you a mobile phone If Num 3 Then MsgBox Num amp wins you a week in Spain If Nu
86. here are two buttons e Some text appears in labels on the form SOFTWARE DEVELOPMENT INT 2 COMPUTING 35 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Each of these items is called an object Each object has properties and some objects including buttons can have program code associated with them so that something happens when a user for example clicks the button Clicking a button is an example of an event VB allows a programmer to create event driven programs To develop a program in Visual BASIC you need to open the VB programming environment To begin with it looks a little complicated but you will soon learn how to use it Here is the same program while it was being developed showing some of the main features of the VB environment VB toolbox VB tool bar Solution explorer window indow Gz Community Help DE gt GS Ol rep oo oe v CheckBox 2 9 CheckedListBox l MonthCalendar Start Page Formi vb Form1 vb Design a3 Club Membership anx Enter your name and age in the boxs below then click the button to register yourself as a member x E Name F Se Properties DateTimePicker Ag AT 4 3 A Label window A LinkLabel ListBox ee ListView Register Quit _ MaskedTextBox Solution Explo
87. hmetical question e g What is 100 x 1007 e ageneral knowledge question e g Who won Big Brother in 20067 Improvements to the program This simple program works fine but there are some obvious changes which would improve it Improvement 1 When you give the wrong answer the program doesn tell you It could be improved by presenting a message which told the user to try again SOFTWARE DEVELOPMENT INT 2 COMPUTING 113 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS To do this you need to add in the following line of code If user_answer lt gt correct_answer Then MsgBox Wrong try again Can you work out where this line of code should go Edit it into your program and check that it works Improvement 2 The program would be improved if it told you how many guesses you made before you got the correct answer To do this we need to include a counter in the loop Here is the pseudocode the new sections are in bold Declare integer variables for the user s answer and the correct answer Declare an integer variable for the counter Set the counter equal to zero Set the correct answer equal to 4 Do e get the user s answer to the question What is 2 2 e add one to the counter e if the answer is not the correct answer display Wrong try again message 6 Until user s answer is equal to the
88. hold the two random numbers to be used for the question Dim user_answer As Integer Dim correct_answer As Integer Dim first second as Integer Dim counter as Integer These lines generate the two random numbers for the question Randomize first Int Rnd 10 1 second Int Rnd 10 1 This displays the value of the counter 0 variables first and second rather correct_answer first second than the numbers 2 2 Do user_answer InputBox What is amp first amp amp second amp counter counter 1 If user_answer lt gt correct_answer Then MsgBox Wrong try again Loop Until user_answer correct_answer MsgBox Well done You took amp counter amp tries End Sub SOFTWARE DEVELOPMENT INT 2 COMPUTING 119 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS One more modification The program only asks one random addition question each time it is run By adding three lines of code we can make it give the user a series of Say six questions We can do this by putting the whole of the middle section of the program inside a For Next loop like this Private Sub btnQuestion_Click generates 6 random question to the user and waits for the correct answer Dim user_answer As Integer Dim correct_answer As Integer Dim first second as Integer Dim counter as Integer
89. i 1 so student_name 1 and mark 1 are used and so on The same thing happens here with i taking the values 0 1 2 3 and 4 in turn so each name and mark are displayed in the list SOFTWARE DEVELOPMENT INT 2 COMPUTING 141 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Implement and test this new version It should work correctly now A S Stages 5 and 6 Documentation and evaluation RA seo As usual you should e print out hard copies of your form and the coding e save your program and tidy up the files into a folder e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability 5 5 Examples using arrays Lucky prize Draw version 1 Stage 1 Analysis Program specification Data flow diagram Design write and test a program which prompts the user to enter 10 names 10 names KE then selects and displays one chosen at random C gt Stage 2 Design We want the user interface to look like Prize Draw this The lucky winner is It has a command button two labels a title and a text box called txtWinner fF The user will enter the 10 names using input boxes by A Programmer 05 01 04 142 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009
90. ing Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 10 Predefined numeric functions There are some standard mathematical calculations that you may want to use in your programs Visual BASIC along with most other high level languages provides predefined functions to carry these out for you We ll take a look at some predefined functions provided by Visual BASIC INT takes a number and removes any fractional part leaving the whole number part CINT takes a number and returns the nearest whole number ROUND rounds a number to any number of decimal places SQRT returns the square root of any number Function Tester program We will use a simple VB program to test these functions e Create a form like this Cappers Jog e Name the text boxes txtEnter and Enter a number Apply txtResult function Result e Name the command buttons btnClear and btnFunction Clear by A Programmer f 18 10 2007 e Write the code for the clear button as you did in Section 3 7 e Copy this code for the btnFunction command button Private Sub btnFunction_Click Dim number result As Single e Save the project and form number txtEnter Text result INT number e Run the program to test the INT function txtResult Text result End Sub As you do this copy and complete a table of testing as shown below SOFTWARE DEVELOPMENT INT 2 COMP
91. k but not answers to programming tasks as many possible correct answers are possible and syntax may vary depending on the version of VB in use 6 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 INTRODUCTION Student guide This teaching and learning material is designed to cover all the skills knowledge and understanding that you need to pass the Software Development unit of Intermediate 2 Computing To achieve this unit you must develop and demonstrate knowledge and understanding of e the principles of software development Section 1 e software development languages and environments Section 2 e high level language constructs Sections 3 and 4 e standard algorithms Section 5 At the end of the unit you will be tested on this knowledge by sitting a short 20 question multiple choice test However it is not only about passing a test You must also develop practical skills in software development using a suitable high level language Almost any programming language can be used but these notes especially Sections 3 to 5 assume that you are using Visual BASIC 2005 EE or VB 2008 EE If you are using a different programming language your teacher or lecturer will need to supply you with other materials for some parts of the unit Your teacher or lecturer will complete a practical skills checklist for you as you work through the practical exercises in these notes
92. lid mark i e one that is over 100 If you tested the program thoroughly you might have discovered that it is still possible to enter invalid data For example the program would accept a negative number which would not be a valid mark in any exam that know We can easily adapt the program to also prevent invalid negative numbers being entered as follows changes in bold using complex conditions Private Sub btnDataEntry_Click Dim mark As Single Do mark InputBox Enter a mark between 0 and 100 If mark gt 100 Or mark lt 0 Then MsgBox That was not a valid mark Loop Until mark gt 0 And mark lt 100 txtValidMark Text mark End Sub Save this program as valid_mark You will use it as a basis for the tasks in section 5 2 Make these changes and test the program again using the following test data Normal 23 55 99 150 10 Extreme 0 100 0 0001 99 999 100 001 Exceptional A lt spacebar gt z 130 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Validation or verification Notice that input validation doesn t prevent wrong data being entered For example if a student had scored 55 in an exam and the operator entered the mark as 56 by mistake the program would accept this data The data would be wrong but still valid The pr
93. m 4 Then MsgBox Num amp wins you 10p If Num 5 Then MsgBox Num amp wins you a meal for two If Num lt 1 Then MsgBox Num amp is too small If Num gt 5 Then MsgBox Num amp is too large End Sub Enter the coding for the Clear button as usual re xy we Stage 4 Testing Devise some test data This should include e some normal data e some extreme data e some exceptional data Run the program using your test data and record the results in a table SOFTWARE DEVELOPMENT INT 2 COMPUTING 87 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Pew X SNA G3 Stages 5 and 6 Documentation and evaluation As usual you should e print out hard copies of your form and the coding e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability Extra task changing form colours You may have discovered that the colour of forms and buttons can be changed using the properties window when you are creating a form Properties such as colour can also be changed during the running of the program as the next example shows 88 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Lucky Winner with colours As w
94. many slabs wide If it has worked correctly save it slabs and cost How many slabs deep If it doesn t work then go back and check for errors Cost of one slab 2 99 Number of slabs required 20 The most common mistakes are to make a spelling error in the name of a variable or a text box so always check these carefully by A Programmer 21 09 07 Total cost 59 8 SOFTWARE DEVELOPMENT INT 2 COMPUTING 57 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 4 Testing Testing is a very important stage in the software development process Proper testing of a commercially produced program may take as long as the implementation We will test this program methodically using normal extreme and exceptional data Normal data is data that you would expect to be input to the program Extreme data is data that is on the limits of acceptability it should work but you need to check to make sure Extreme data could include zero or very large numbers or numbers close to any limit relevant to the program Exceptional data is data that shouldn t be input under normal use for example entering a letter when asked for a number or clicking a command button when there is no data in the input text boxes It is best to draw up a table of testing choosing suitable test data as shown below Fill in the expected results column
95. name so it has to be able to store it in between Now we need to turn the pseudocode we wrote at the design stage into Visual BASIC Pseudocode Visual BASIC Store the name name txtName Text Display the message MsgBox welcome to VB amp name These two lines need a little explaining name txtName Text This line is best read from right to left it tells the computer to take the text from the text box called txtName and store it in the memory location called name MsgBox Welcome to VB amp name The final line tells the computer to create a message box on the screen and to display the words Welcome to VB followed by whatever is stored in the location called name The commas and speech marks must all be there in the correct order If you have entered all that correctly it should look like this A Formi vb Start P Form1 vb Design Notice the extra blank lines _ ___ _ OT RESNO btnMessage v 2 Click they don t do anything but E ETET they make the program more readable just like gaps A Private Sub btnMessage Click ByVal sender As System Obje between paragraphs in an by A Programmer on 14 09 07 essay or report Dim name As String name txtName Text Now save the program again click Save all MsgBox Welcome to VB amp name End Sub End Class Note VB keywords are displayed in blue comment lines in green text in red an
96. name and a welcome message 38 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 1 Analysis Start by thinking about what data goes in and what data comes out of the program while it is running A data flow diagram is a good way of analysing this Start by representing the program as a blob Think what information comes out of the program Name and welcome message Show this as an arrow coming out of the blob Now think what information needs to go into the program to give this output Name and Show this as an arrow going name in to the blob welcome message Copy this diagram you have drawn your first data flow diagram SOFTWARE DEVELOPMENT INT 2 COMPUTING 39 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 2 Design user interface Next we need to think about what we want the program to look like We can sketch out how we want the form to look like this My First Program in VB Click for by A Programmer 15 12 03 message Our form has e atitle caption at the top e a label Enter your name e a text box to type your name into e a button to activate the message e another label with your name and the date If you re wondering where the message is going to appe
97. nd 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Testing the UCase function Run the String Function Tester program Record the results in a table like the one below adding a few tests of your own UCase predefined function Input string Output string Comment Hello world HELLO WORLD 123 One Two Three 2 amp Write a brief statement summarising the effect of the UCase function Testing the LCase function Edit the coding of the Function Tester 2 program Change string _out UCase string_in into string_out LCase string_in 72 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Run the program to test the LCase function Record the results in a table like the one below adding a few tests of your own LCase predefined function Input string Output string Comment Hello world HELLO WORLD 123 One Two Three 28 Write a brief statement summarising the effect of the LCase function Testing the Len function Edit the coding of the String Function Tester program Change string_out LCase string_in into string_out Len string_in Run the program to test the Len function Record the results in a table like the one below adding a few tests of your own Note Make sure there are no
98. nd grade display the values of these variables e inserts a comma and space after the initials e grade inserts a sign comma and the word grade after the percentage mark SOFTWARE DEVELOPMENT INT 2 COMPUTING 93 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS All the above is the actual message then e the two commas separate the message from the title e student result at the end is the title of the message box display message in format AE 70 to 2 dec places grade A percent System Math Round percent 2 MsgBox init1 amp init2 amp amp percent amp grade amp grade student result End Sub Stage 3 Implementation e Start a new project called exam_grader e Create aform as above e Name the text boxes txtMax txtName txtSurname and txtMark e Name the buttons btnOK and btnClear e Enter the coding for the OK button e Enter the usual coding for the Clear button SE 7 Stage 4 Testin IAM Ses 9 Devise some test data This should include e some normal data e some extreme data e some exceptional data Run the program using your test data and record the results in a table Stages 5 and 6 Documentation and evaluation Don t print out your program or write documentation or an evaluation report yet as you are going to make some minor improvements to th
99. nd so does VB List 3 are all numbers with fractions We call these real numbers VB calls them single SOFTWARE DEVELOPMENT INT 2 COMPUTING 51 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Ree Activity Classify each of the following as integer string or single a 150 b Bob the Builder c 49 99 d EH16 1AB e 0 5 f 500 g 583 h 123 i Albert j 99 99 k 0 00006 l 5 High Street Visual BASIC needs to know what type of data it will be storing and processing in any program To do this we declare variables at the start of the program using lines like Dim no_in_class as Integer Dim name as String Dim price as Single When the VB system reads these statements at the start of a program it sets up a storage space of the appropriate type in the computer s RAM and labels it with the variable name given Of course these are electronic storage locations but it is useful to imagine them as labelled boxes in which data can be stored like this An integer variable called no_in_class storing value 18 no_in_class Albert ee FY called name A single variable called price storing value 27 99 52 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED These storage boxes are called variables becaus
100. ntation which helps me remember ADITDEM Documentation Evaluation Maintenance Next we will take a closer look at each of the stages Analysis Design Implementation Testing Documentation Evaluation Maintenance You might be able to make up a better mnemonic than this one so long as it helps you then it s OK 1 4 Analysis The main purpose of the analysis stage is to be absolutely clear about what the program is supposed to do Often a new program will start from a rough idea Before getting started it is important to turn the rough idea into an exact description of how the program will behave What will it do What are the inputs and the outputs What type of computer is it to run on All these questions and many more must be asked and answered at this stage SOFTWARE DEVELOPMENT INT 2 COMPUTING 15 Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS The result of this is the production of a program specification agreed by both the customer whoever wants the program written and the developer the person or company who is developing the program 1 5 Design Inexperienced programmers are often tempted to jump straight from the program specification to coding but this is not a good idea It is worth spending time at the design stage working out some of the important details including how the program will look on the screen how the user will interact with the p
101. ocess of preventing incorrect data being entered is called verification Many commercial data processing systems involve both verification and validation In this unit we are only considering validation Standard algorithm for input validation The coding for input validation always follows a standard pattern The details will vary depending on the specification of the program but the same pattern can always be used This standard pattern saves programmers time when designing programs A pattern like this is called a standard algorithm Here is a simple version of a standard algorithm for input validation It involves a conditional loop and an If statement like this Do Prompt user for valid input If input is invalid warn user Loop until input is valid Adapting Program 4 4 We can use the standard algorithm for input validation to improve the exam grade program we developed in Section 4 4 Here is the section of code used to input the data store user inputs max_mark txtMax Text first_name txtName Text surname txtSurname Text mark txtMark Text As it is at the moment you could enter any mark into the txtMark text box SOFTWARE DEVELOPMENT INT 2 COMPUTING 131 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Let s alter the coding so that it won t accept the following types of invalid marks e no marks less than 0 e no mark
102. ode as before If you need a reminder how Save your program and tidy up the files into a to do these single folder look back to page 45 x 2 Write a brief user guide AM 7 Y CAS AD Write a brief technical guide Al N Stage 6 Evaluation av PE Pa PY As before write a brief report answering these questions e Does the program fulfil the specification e ls the user interface appropriate e ls the program coding readable SOFTWARE DEVELOPMENT INT 2 COMPUTING 59 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 7 Adding a Clear button One possible criticism of the previous program is that once you have used it once you need to delete the contents of the text boxes before using it again We can easily improve this by adding a second command button which will clear each of the text boxes Add a second button Position it on the form Name it btnClear Make its text Clear Double click on the clear button A code window will appear with the start and finish of the coding for the clear button Complete this as below r a Belinda s Slab Calculator How many slabs wide Calulate slabs and cost Clear Number of slabs required How many slabs deep Cost of one slab by A Programmer 21 09 07 Total cost Private Sub btnClear_Click clears all text boxes t
103. of steps from beginning to end whatever data you input This limits the usefulness of the program Imagine a game program that was exactly the same every time you ran it In this section you will learn how to make programs that do different things depending on the data that is entered This means that you can write programs with choices for the user and with different options and branches within them To do this in Visual BASIC is very easy as you will see Here are some examples of VB statements that use the keywords IF THEN and ELSE If Number lt 0 Then txtAnswer text That was a negative number If Reply No Then MsgBox Are you sure If Salary gt 5000 Then Pay Salary Tax Else Pay Salary If Guess Correct_Answer Then MsgBox Well Done Else MsgBox Wrong try again The first two examples follow a simple pattern If condition Then action We will study using this pattern in Section 4 2 82 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS The last two examples follow a slightly more complex pattern If condition Then action Else alternative action We will study using this pattern in Section 4 3 Note We will use the following symbols in this section gt greater than lt less than gt greater than or equal to lt
104. omputer Systems unit all characters letters numerals and punctuation marks are stored in a computer system in anumeric code called ASCII American Standard Code for Information Interchange The Asc predefined function returns this code trick Chr takes any number and returns the character which this ASCII code represents Testing the Chr function Edit the coding of the String Function Tester program Make the following changes Change To Private Sub Private Sub btnFunction_Click btnFunction_Click Dim string_in As String Dim number_in As Integer Dim number_out As Integer Dim string_out As String string_in txtEnter Text number_in txtEnter Text number_out Asc string_in string_out Chr number_in txtResult Text number_out txtResult Text string_out End Sub End Sub Note You should also change the label on the form to read Enter a number rather than Enter a string Run the program to test the Chr function 76 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Record the results in a table like this adding a few tests to check that Chr turns any ASCII code into the character it represents Chr predefined function Input number Output character Comment 65 66 97 98 63 20 Write a brief statement summarising the effect
105. orks allow you to record macros but don t allow you to edit the code as you can in MS Office If you have time you could explore any other applications that you use to see if they have a macro facility SOFTWARE DEVELOPMENT INT 2 COMPUTING 33 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Questions What is a macro What type of language is sued to write macros What are the advantages of using macros Describe two situations where a macro could be useful Seach Noli 34 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Section 3 High level programming getting started 3 1 Introducing Visual BASIC For this section of the course you are going to learn to develop programs using a high level language called Visual BASIC often shortened to VB The first stage is to become familiar with the Visual BASIC environment Here is what a simple Visual BASIC program might look like a gt Club Membership Caption Enter your name and age in the bows below then click the button to register yourself as a member Label Text box Button Register Notice the following features of the program e The whole program appears as a form e At the top of the form there is a caption club membership e There are two text boxes for entering the name and age e Atthe bottom t
106. orry about all the stuff that appears automatically in here You will learn what it means later But don t delete or alter it in any way Double click on the command button to open a code window It should already have the first line of code which should read Private Sub btnCalculate_Click Enter the first two lines of code as comment lines as you did in the previous example code for the Calculate button by A Programmer 21 09 07 The next stage is to declare all the variables that the program will need It will need to store e number of slabs wide a whole number e number of slabs deep a whole number e the cost of a single slab a real number as it could be 2 99 e the total number of slabs a whole number e the total cost a real number This can be coded into two lines like this Dim wide deep no_of_slabs as Integer Dim slab_cost total_cost as Single The next lines of code are translated from the pseudocode as shown below Pseudocode Visual BASIC Store the number of slabs gt wide txtWide Text wide Store the number of slabs deep txtDeep Text deep Store the cost of one slab gt slab_cost txtCost Text Calculate the number of slabs gt no_of_slabs wide deep required Calculate the total cost gt Oa Poal gt Naudlzsiabs slab_cost Display ine number Ols ape gt ixtTotalNumber Text no_of_slabs required Display the t
107. otal cost gt ixtTotalCost Text total_cost 56 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED If you have done all of this correctly CIERRE caog you should have a form that looks like this How many slabs wide Calulate slabs and cost How many slabs deep Cost of one slab Number of slabs required by A Programmer 21 09 07 Total cost and a code window like this _ Form1 vba Form1 vb Design a If it all looks correct then o binCalaulate x 4 click lv J Public Class Formi e Run the program to make sure it is working correctly Private Sub btnCalculate Click ByVal sender A code for Calculate button by A Programmer 21 09 07 Dim wide deep no of slabs As Integer Dim slab cost total_cost As Single e Enter the following data wide txtWide Text deep txtDeep Text slabs wide 4 slab_cost txtCost Text slabs deep 5 no of slabs wide deep cost per slab 2 99 total _ cost no of slabs slab cost txtTotalNumber Text no_of slabs e Click the button txtTotalCOst Text total cost P End Sub LEnd Class lv KA m ma The following results should appear in the result text boxes e total number 20 a Belinda s Slab Calculator e total cost 59 8 as shown below How
108. ou will learn more about these in Section 2 1 7 Testing We thought a bit about testing at the start of this section Whether we are talking about a new TV a new item of clothing or a new computer program the manufacturers will spend a great deal of time in testing This testing will be carefully planned to test a wide variety of conditions We can divide this up into three types of testing Testing normal conditions Making sure the program does what it should do when used normally Testing extreme conditions Making sure the program can handle situations that are at the edge of what would be considered normal Testing exceptional conditions Making sure the program can handle situations or inputs that it has not been designed to cope with You will see examples of all of these in Section 3 1 8 Documentation When you buy a product whether it is a computer program or anything else you usually get some kind of user guide with it This tells you how to use the product It might also contain a tutorial taking you through the use of the product step by step 18 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS Some software comes with a big fat book called user guide or manual others come with the user guide on a CD As well as documentation for the user of the software there should also be a technical guide of some sort This gi
109. ox so it is deep enough for two lines of text This allows the text in the text box to word wrap at the end of a line Belinda McSporran73 Name Belinda McSporran Number 73 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Also in the code change txtDisplay text players_name amp squad_number into txtDisplay text Name amp players_name amp VbCrLf amp Number amp squad_number this puts in the VbCrLf forces a If an item has speech marks word Name and a new line Visual then it is copied exactly if not colon followed by BASIC carriage then the value of the variable is 2 spaces return line feed displayed After making these changes to improve the appearance of the output you should carry out methodical testing of the program Assuming that the program displays the name and squad number of the player correctly you only need to test that it calculates averages correctly pany ew Draw up a table of testing with some e normal data e extreme data e exceptional data If there are any errors correct them Save and print the program Summarise your test results by completing these three sentences e The program gives the correct result if e The program gives a wrong answer if because e The program cannot give an answer if Stage 5 Documentation ey
110. p is too small If Number gt 5 Then MsgBox Number amp is too large End Sub You can see that a high level language has features that make it similar to a human language the use of ordinary words for example This means that the implementation is often carried out using similar tools to those used for writing an essay or report For example cut and paste would be useful when typing the program shown above To write an essay or report you would normally use a word processing package High level language programs can also be written using a word processing package The source code can be saved as a text file which can then be translated into machine code by a compiler However some software development environments provide a text editor which incorporates many of the usual features of a word processor The most useful of these is probably the ability to cut and paste sections of code Activity Consider the software development environment you are using ee KS for the programming section of this unit Does it have a text I j editor or do you use a separate word processing package What useful text editing features does it incorporate 28 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT 2 7 Scripting languages and macros Most of this unit is concerned with the process of developing programs written in a high level languag
111. pected Run the program using your test data and record the results in a table av J Pa 4 e Stages 5 and 6 Documentation and evaluation IAL As usual you should e print out hard copies of your form and the coding e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability Extra task Modify the program so that it asks your age and gives you the message You can learn to drive if you are 17 or over Note You will need to use one of the symbols listed in Section 4 1 SOFTWARE DEVELOPMENT INT 2 COMPUTING 85 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS 4 3 Multiple Ifs C d TEG lt Example Lucky Winner The problem A program is required that will select a suitable prize depending on which number between 1 and 5 is entered by the user Stage 1 Analysis program specification Design write and test a program to e prompt the user to enter a number between 1 and 5 e store the number e output an appropriate message Enter a 1 You have won a colour TV Enter a 2 You have won a mobile phone and so on There is no prize if the number is not between 1 and 5 Stage 1 Analysis data flow diagram appropriate message on screen any number 2 Design interf ee eg ve ee T
112. ple Finding a minimum This algorithm works its way through a list of numbers and finds the number with the lowest value For example here is a list of daily midday temperatures recorded at a weather station during February 2003 Date 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Temperature C 4 6 5 7 11 9 8 5 3 4 13 6 Z 4 Date 15 16 17 18 19 20 21 22 23 24 25 26 27 28 er de 6 l2 13 I8 le 12 10 11 9 le 11 8 l6 The finding a minimum algorithm would search through all the daily temperatures in the list and find the lowest one In this case it would be 2 C on the 17th of the month The algorithm would return the value 2 the actual minimum temperature 134 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Other examples could include e finding the lowest mark in a list of exam marks e finding the winner in a list of golf scores e finding the youngest member in a club membership list It can also be used to search a list of names to find the first if arranged alphabetically this is possible because strings are stored as ASCII codes which are numbers Finding a maximum This algorithm works its way through a list of numbers and finds the number with the highest value In the exam
113. ple above it would find 12 C on the 21st of the month Counting occurrences This algorithm also works its way through a list of numbers As it does so it counts how many occurrences of a given value there are in the list For example if the counting occurrences algorithm was applied to the list of midday temperatures with a search value of 9 C it would return the answer 2 as there are 2 days the 6th and the 24th when the temperature was 9 C Date 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Temperature C 4 6 5 8 11 9 8 5 3 4 13 6 Z 4 Date 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Temp C 5 l6 2 3 a e 12 10 11 9 6 J 11 8 l6 Linear search The final standard algorithm which you need to know about is called linear search The idea is simple it searches through a list looking for a particular item and reports where the item is found In the above list of temperatures if linear search were given the search value 7 C it would return the answer 13 as 7 C is found at position 13 in the list SOFTWARE DEVELOPMENT INT 2 COMPUTING 135 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Questions 1 Look at these lists of data items 1 27 3 1 999 1 0 001 2 15 6 2 333 2 0 002 3 9 93 3 500 3 0 010
114. ps when the Loop While condition condition becomes false Do Whe canaliton Only executed while the Line s of code to be dee Dee ha Do While Loop condition is true as it is repeated on tested at the beginning Loop Do need to know about all four types No for this unit it is enough to be able to use one type of conditional loop SOFTWARE DEVELOPMENT INT 2 COMPUTING 127 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Congratulations You have completed Section 4 Here is a Summary of what you should now be able to do using VB Y p TE 4 design and create a form using text boxes command buttons labels and captions change the properties of an object analyse a problem using a data flow diagram write pseudocode convert it into VB code and assign it to an event declare string integer and single real variables use text boxes message boxes and input boxes test a program using normal extreme and exceptional data use a range of predefined functions write brief user guides and technical guides for simple programs evaluate a program in terms of fitness for purpose user interface and readability use conditional statements involving If Then Else and End If use simple and complex conditions involving comparison operators And Or and Not create fixed loops using For Next create conditional loops using
115. r 3 Then Me BackColor Color Green MsgBox Number amp wins you a holiday in Spain End If If Number 4 Then Me BackColor Color Yellow MsgBox Number amp wins you 10p End If If Number 5 Then Me BackColor Color Gold MsgBox Number amp wins you a day at the beach End If If Number lt 1 Then MsgBox Number amp is too small If Number gt 5 Then MsgBox Number amp is too large End Sub Where multiple actions are required a conditional statement is of the format If condition Then Action 1 Action 2 Action 3 and so on End If SOFTWARE DEVELOPMENT INT 2 COMPUTING 89 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Practical task 1 adapt the Lucky Winner program to fulfil this specification Design implement and test a program that asks the user to enter a grade A B C D or F and gives you messages like A means you got over 70 B means you got between 60 and 70 and so on The form should change colour depending on the grade entered As usual you should e print out hard copies of your form and the coding e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability Practical task 2 Adapt the AB_code program to correctly code Z and z Remember the
116. r InputBox Enter the player s number game_1 InputBox Score in 1st game game_2 InputBox Score in 2nd game game_3 InputBox score in 3rd game average game_1 game_2 game_3 3 txtDetails Text players_name amp squad_number txtAverage Text Clint average End Sub 68 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Notes a InputBox Enter the player s name generates a box on the screen like this whatever the user types into the text box is stored in the variable players_name when the OK button is clicked b The amp between players_name and squad_number simply makes the basketball X Enter the player s name Cancel contents of these two string variables follow on after each other in the txtDetails text box c Clnt average turns the value of average into the nearest whole number see Section 3 10 Alternatively you could use System Math Round average 0 Stage 4 Testing e Run the program to make sure it works You will notice that the output looks like this It would be better to make it look like this To do this make the following two changes On the form e select the txtDetails box e scroll down the properties window to find multiline e change the multiline property to true e resize the text b
117. r counter Until pin correct_pin Or counter 3 3 5 If counter 3 then display If counter 3 Then txtMessage Text message 3 The card is being kept for security Variables required counter integer pin integer correct_pin integer Stage 3 Implementation e Start a new Visual BASIC project e Create a form as above e Name the command button btnStart e Name the text box txtMessage e Enter the code for the command button declare all required variables e Save the project and form in a new folder Stage 4 Testing Create some suitable test data and use it to test the program Test data 1 Test data2 Test data 3 Test data 1347 9999 1234 8888 4321 1347 9999 Comment SOFTWARE DEVELOPMENT INT 2 COMPUTING 125 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS ray aw Stages 5 and 6 Documentation and evaluation As usual you should e print out hard copies of your form and the coding e save your program e write a short user guide and technical guide e write a brief evaluation of the program in terms of its fitness for purpose user interface and readability Task Password Checker Modify the program to e prompt the user to enter a password which could contain letters as well as numbers e allow five attempts at guessing the password Note If you want to keep
118. racter uncoded_char A string variable to hold the coded character coded_char An integer variable for the ASCII code of the input character ascii_uncoded An integer variable for the ASCII code of the coded character ascii_coded Complete the code for the btnCode button by using Dim to declare these four variables and converting each step of the pesudocode into VB code Private Sub btnCode_Click coding for the Code command button by A Programmer on 19 10 07 Dim uncoded_char coded_char As String Dim ascii_uncoded ascii_coded As Integer uncoded_char txtin text Step 1 ascii_uncoded Asc uncoded_char lt ______ Step 2 R 2 a Bn ns ascii_coded ascii_uncoded 1 Step 3 coded_char Chr ascii_coded a Step 4 txtOut text coded_char a Step 5 End Sub Code the Clear button in the usual way Save the project as AB_code 80 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 4 Testing Run some tests using normal extreme and exceptional data Record your results in a table Stage 5 Documentation gt As usual write a brief user guide and technical guide for the Cw j program and attach a hard copy of the code and the form layout Stage 6 Evaluation aS Write a brief evaluation of the program You should include a 7 NA fA note about the letter s which it codes incorrectly You will le
119. rer i Solution Explorer SAELE 28 testi Sa My Project ES Form1 vb Properties e NotifyIcon 2 Form1 System Windows s Form Py E a az 3 Z Error List ix ControlBox e Q 0 Errors 1 0 Warnings i 0 Messages eee b ied DoubleBuffered Description File Line Colums Project Enabled Font Microsoft Sans Serif ForeColor HM Controirext FormBorderStyle Sizable HelpButton False k Font The font used to display text in the control Ready TE 15 15 T 300 x 258 At the top is the menu bar with the usual menus File edit and some specialised VB menus Below this is the VB toolbar The item you will use most is the gt icon which you use to run a program Down the left side is the toolbox from which you will select objects to place on your form The form appears in the form window in the middle of the screen 36 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED On the right side of the screen you will see the solution explorer window and the properties window All of these will be explained as you work through the examples Important advice If any of the windows disappear unexpectedly you can get it back by selecting it in the View menu We are going to learn to develop Visual BASIC programs using the steps of the software development process that you have already m
120. riable names SOFTWARE DEVELOPMENT INT 2 COMPUTING 61 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 9 Working with numbers tasks For each task below you should e clarify the specification analysis e draw a data flow diagram analysis e sketch the user interface design e write pseudocode for the button design e create the form implementation e write the coding implementation e draw up a table of testing e test the program with normal extreme and exceptional data e write brief user and technical guides documentation e evaluate the program 1 Design write and test a program to calculate the average of six test marks 2 Design write and test a program to calculate the volume of a cylindrical water tank using the formula volume TT rh r radius of tank h height of tank 3 Design write and test a program to calculate the number of points gained by a football team given the number of wins draws and lost games assuming a win is worth 3 points a draw 1 point and no points for a lost game 4 Design write and test a program to calculate the storage requirements in megabytes for a bit mapped graphics The inputs should be the breadth and height of the graphic in inches the resolution in dots per inch and the colour depth in bits per pixel 62 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teach
121. roduct is developed because the process is essentially the same For example think about the process of developing a new model of television Stage 1 Analysis Before a new product is developed someone within the company probably in the marketing department analyses what people want They consider which products are selling well look at what rival companies are producing and maybe even carry out a survey to see what people want From this they can work out which features are required in their newest model including its size target price range and various technical requirements They use this information to produce a specification for the new model of TV This states clearly all the features that it must have 10 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS Stage 2 Design The next stage is to turn the specification into a design Designers will get to work alone or in groups to design various aspects of the new TV What will it look like How will the controls be laid out Sketches will be drawn up and checked against the specification Another team of designers will be planning the internal circuitry making sure it will allow the TV to do all the things set out in the specification Stage 3 Implementation Once the design phase is over engineers will get to work to actually build a prototype Some will build the case according to t
122. rogram and how the program might be structured Program designers use a variety of methods for describing the program structure Two common ones are called pseudocode and structure diagrams There are many others but we will only consider these two It is easy to understand these if we think about an everyday example rather than a computer program Think about making tea Here is a list of instructions for this task Get a mug out of the cupboard Put a teabag in it Boil the kettle Pour boiling water from the kettle into the mug Stir daa el be era This is an example of pseudocode It is a numbered list of instructions written in normal human language in this case English It doesn t go into all the details but it gives the main steps Another way of showing this is as a structure diagram It could look like this Making tea Get mug Put Boil kettle Pour water from teabag in from kettle cupboard mug into mug Each instruction goes into a separate box You read pseudocode from top to bottom You read a structure diagram from left to right 16 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS A AJ Pa DAS Now try a gt Activity ouple for yourself Here are some simple tasks Q e Going to school e Going to New York e Having a shower e Phoning a friend S e Becoming a millionaire b Choose any two
123. rogram specification Design write and test a program to e prompt the user to enter a player s name squad number and points scored in games 1 2 and 3 e calculate the player s average score rounded to the nearest whole number e display the player s name squad number and average clearly on a form Stage 1 Analysis data flow diagram Players name Players name Squad tet ae a ee eed ae Squad number Score 1 _ gt f E a points Score 2 Score 3 Stage 2 Design user interface This time we will use input boxes which are like message boxes but used for input to enter the data so the form only needs a command button two text boxes for the output and the usual labels and caption Basketball Team Manager Player details by A Average Programmer score 18 10 2007 66 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 2 Design pseudocode When the user clicks on the start button input boxes should pop up to input each of the six items of data then the average should be calculated and the results displayed In pseudocode prompt for and store the player s name prompt for and store the player s number prompt for and store each of the three scores calculate the average score display the player s name and number display the player s average s
124. s greater than the maximum mark for the exam All you need to do is replace the single line mark txtMark Text with an input validation loop like this Do mark InputBox Enter a valid mark If mark gt max_mark Or mark lt 0 Then MsgBox That was not a valid mark Loop Until mark gt 0 And mark lt max_mark txtMark text mark Test the program to ensure that the input validation is working Extra task Change the line max_mark txtMark Text to ensure that the user cannot enter a maximum mark less than 0 or greater than 200 by replacing it with a standard input validation loop 132 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS 5 2 Input validation tasks Adapt the valid_mark program from Section 5 1 to do each of the following You should start by exporting the valid_mark program as a template so that you can base each of these task on the template that way you won t need to start each program from scratch e Prompt the user to enter their age Do not accept ages less than 0 or greater than 120 as valid ages e Prompt the user to enter a 4 digit PIN The program should only accept the PIN if it is 4 digits long Hint Make it an integer what is the smallest and largest value e Prompt the user to enter what year they are in at school Only accept 1 2 3 4 5 or 6 as valid years
125. sage Text welcome to VB amp name Run the program The result will look yo My first Program in VB BAX something like this depending on where you placed your label Enter your name Albert Einstein Welcome to VB Albet Einstein click for message by A programmer 15 09 07 The alternative is to make the output appear in another text box SOFTWARE DEVELOPMENT INT 2 COMPUTING 49 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Output to a text box Again two changes are needed to the program Firstly add a second text box to the form and name it txtMessage Secondly change the line of code from MsgBox welcome to VB amp name to txtMessage Text welcome to VB amp name Run the program a My first Program in VB Joey The result will look something like this Enter your name Albert Einstein depending on where you placed your second text box click for message Welcome to VB Albert Einstein by A programmer 15 09 07 Choosing the style of output You have now seen three ways of outputting the same message e inamessage box e directly on the form in a label e ina text box on the form This may be stated in the program specification If not itis a decision that you can make at the design stage 50 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning an
126. ss Formi Al e Double click on the PAESI i P ick ByVal senger As System Obje button Class A code window should appear Be careful not to change any of the text which appears here Note the button s name btnMessage and the event click which will activate this code appear automatically You will enter your VB coding for this button in the space between the first and last lines which have been inserted automatically v e Enter the lines of code which are highlighted below in bold Read the explanatory notes as you go along so that you understand what the code does The first two lines of code are as follows code for the Message button by A Programmer on 21 09 07 These two lines start with a single apostrophe which means that they are comment lines they are ignored by the computer but make the program more readable It is always good practice to start any new section of coding with some comment lines like these SOFTWARE DEVELOPMENT INT 2 COMPUTING 43 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED The next line is Dim name As String This line tells the computer to set aside a storage location in memory which will need to hold a string of characters and to call it name we know this is required from the data flow diagram remember the program will input a name then output the
127. st of programs that have used recently e Microsoft Word the word processing program that use regularly use three versions of it Word 2000 Word 98 for MacOS 8 Word v X for MacOS X e Microsoft Excel spreadsheet used to keep charity accounts for which am the treasurer e ClarisWorks 4 integrated package mainly use its word processor and simple database sections e Internet Explorer both PC and Mac versions for browsing the web e Safari web browser for MacOS X e three different email clients Netscape Communicator MS Outlook and Mail e iPhoto for organising my digital photographs e iMovie for editing digital movies e Adobe Photoshop for editing digital photographs e Citrix ICA thin client allows me to connect to my work computer from home e Toast for burning CDs 8 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 SOFTWARE DEVELOPMENT PROCESS e Print to pdf a shareware program for creating pdf files e Adobe Acrobat and Preview for viewing pdf files e Macromedia Flash for developing animated graphics e Home Page an ancient but reliable web page editor e some game programs e Symantec Anti virus suite But that s not all On each computer that have used a program or group of programs called the operating system must have been running So must add the following to my list e Windows 97 on the ancient laptop am usin
128. t do is called the program specification SOFTWARE DEVELOPMENT INT 2 COMPUTING 53 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 1 Analysis program specification Design write and test a program to e input two whole numbers the no of slabs wide and no of slabs deep e multiply them together no of slabs needed no wide x no deep e input the price of a single slab e multiply to get the total price e display the results number of slabs required and total cost The program should work for any numbers Stage 1 Analysis data flow diagram A blob for the program Nuinbarerelabe What information comes out of the program Total cost What information does the program need as input No of slabs wide Number of slabs No of slabs deep Cost of a slab a mas Total cost 54 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Stage 2 Design user interface Sketch out how we want the Belinda s Slab Calculator form to look veh How many slabs wide This time we will use text boxes for both input and output of data Calculate slabs and cost How many slabs deep This form has Cost of one slab e a title caption e six labels Number of slabs required e three text boxes for input by A
129. t to read Enter your name do this in the properties DatePicker window Move the label to wherever you want it to appear on the form e Add a second label with your name and today s date in the same way ListBox 3a ListView SOFTWARE DEVELOPMENT INT 2 COMPUTING 41 Learning and Teaching Scotland 2009 Common Con Toolbox ix A HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED Sry Rowe e Next add a text box Double click on the text box icon from the c padi 2 RadioButton toolbar me ee 5 RichTextBox You may need to scroll down to find it they are listed in alphabetical order Use the properties window to change its name property you ll need to scroll up the properties window to find it from TextBox1 to txtName Toolbox ix All Windows F A Common Con Pointer e Finally add a button Double click on the button icon on the ao ab Button toolbar e Use the properties window to change the button s text to click for message and its name to btnMessage Re size it and position it on the form a3 My first Program in VB aA If you ve done all that correctly your form should Enteryourname now look like this If not don t worry ask your teacher for help it gets very confusing at this stage with lots of things that can go wrong but you ll soon get the hang of it by A
130. tMessage ltems Add Have a nice day IstMessage ltems Add Have a nice day IstMessage Items Add Have a nice day End Sub IstMessage ltems Add simply adds the text to the items displayed in the list box SOFTWARE DEVELOPMENT INT 2 COMPUTING 97 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Here is a second version of the program that uses a FOR NEXT loop to cut down the amount of coding required Private Sub btnLoop_Click code to display 10 greetings on the screen Alter the coding as by a much better programmer shown and run the using a FOR NEXT loop program again Dim counter As Integer It does exactly the same but takes much For counter 1 To 10 less coding IstMessage ltems Add Have a nice day Next End Sub You might be wondering why we used a list box instead of displaying the output in a text box or a label A list box allows multiple items to be displayed without overwriting each other 4 8 Repetition using For Next In this example we will develop another program to display a repeated message in a list box Stage 1 Analysis Program specification Data flow diagram Hello Hello message Design write and test a program to display the message Hello Hello Hello 25 times 98 SOFTWARE DEVELOPMENT INT 2 COMPUTING
131. ter the word END after entering all the names The loop can then continue until name END Pseudocode Visual BASIC coding 1 Clear the list box IstNames Items Clear 2 Set a counter equal to zero counter 0 3 Do the following Do 3 1 prompt the user to enter a name name InputBox Enter a name or END 3 2 add the name to the list box IstNames Items Add name 3 3 extract the first letter of the name initial Mid name 1 1 3 4 if the first letter is A add 1 to the counter If initial A Then counter counter 1 3 5 until the user enters end Loop Until name END 4 Add the counter to the list box IstNames Items Add counter Variables required counter integer name string initial string e Start a new Visual BASIC project e Create a form as above Stage 3 Implementation e Name the command button btnStart e Name the listbox IstNames e Enter the code for the button declare all required variables e Save the project and form in a new folder 122 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Test the program with the following sets of test data and add some more of Stage 4 Testing your own Test data Testdata Test data 1 2 3 Test data Andrew
132. times the section of program is to be repeated What about times when the number of repetitions is not known in advance For example a quiz program might give the user repeated chances to get the answer correct The programmer doesn t know in advance whether the user will get the question right the first time or take two three four or more attempts In this type of situation the programmer needs to use another kind of loop Visual BASIC provides several other types of loop We will use a type called Do Loop Until The pattern syntax for this type of loop is very simple Do Line s of code To be repeated Loop Until condition 112 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Here is a simple example Set up a form like Enter the following coding for the button this Private Sub btnQuestion_Click Se ee Jog generates a question to the user aaa z and waits for the correct answer Arithmetic tester v 1 Dim user_answer As Integer lick f penton Dim correct_answer As Integer by A Programer 13 03 09 correct_answer 4 Do user_answer InputBox What is 2 2 Loop Until user_answer correct_answer MsgBox Well done End Sub Run the program Does it behave as predicted Adapt the program to ask e adifferent arit
133. tland 2009 LANGUAGES AND ENVIRONMENT Instructions and commands made in these binary digital form for processors are known as machine codes Here are a few machine codes for a 6502 processor Not very easy to understand are they 10101001 00000001 Se 10000101 01110000 10100101 01110000 There are several problems with machine code e machine codes for different processors are different e they are very hard for humans to understand and use e they take up a lot of space to write down e itis difficult to spot errors in the codes Unfortunately processors don t understand anything else so machine code has to be used The earliest computers could only be programmed by entering these machine codes directly It was a slow process easy to get it wrong and very difficult to track down and fix any bugs in the programs Machine codes are an example of low level languages understood by the low level components of the computer system the processor and other electronic circuits To get round these difficulties computer scientists invented high level languages High level languages are similar to human languages Instead of using binary codes they use normal words For example the computer language BASIC uses words like PRINT IF THEN REPEAT END FOR NEXT INPUT and so on That means that high level languages are easier to understand than machine code and are more readable that is it
134. uestions e displays Well done right first time if the user gets it right first time e displays Keep practising You took X tries to get it right otherwise ee KS Test the program using normal extreme and exceptional data Cw VJ Write brief user and technical guides and an evaluation report 4 15 More examples using Do Loop Until Example 4 15 1 Class lists Design write and test a program for a teacher The program should prompt the user to enter any list of names which will be displayed on the screen The program should count how many of these names begin with the letter A and display this information at the end of the list Stage 1 Analysis Data Flow Diagram List of names Names entered at keyboard Number of As Stage 2 Design We want the user interface to look like this It has a command button a title and a list box Click to called IstNames enter names Next we design the list of steps pseudocode and then the coding for the command button SOFTWARE DEVELOPMENT INT 2 COMPUTING 121 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Q We will need to use a loop Should it be a For Next loop or a Do Loop Until A As we don t know in advance how many names there will be in the list we need to use a Do Loop Until Q What condition will we use to stop the loop A Ask the user to en
135. upported although it might be possible to use it in this way Students will need significant tutor support particularly while attempting the practical programming sections of the unit This support would include giving help with the complexities of the Visual BASIC environment providing extra example programs where a student needs reinforcement activities and emphasising key teaching and learning points as they occur All the examples provided are exemplified in Visual BASIC VB 2005 EE Express Edition and the same coding should work in VB2008 EE Minor amendments might be required to run the programs in other versions of VB net Users of versions VB5 or VB6 should use the original version of these materials published and distributed by Learning and Teaching Scotland This software development environment and programming language has been chosen as it is one in common use in Scottish schools at SOFTWARE DEVELOPMENT INT 2 COMPUTING 5 Learning and Teaching Scotland 2009 INTRODUCTION present However the SQA unit specification does not require any particular language or environment so the examples could be adapted and or substituted by examples in any other structured procedural high level language To facilitate this the examples avoid where possible constructions that are very specific to VB and that are not easily converted into other languages Answers to questions are provided at the end of the pac
136. ur computer without needing to be translated Questions 1 Name the two main types of translator programs 2 Which one translates a whole program into machine code before it is executed 3 Which one translates a program line by line as it is being executed 4 Why do machine code programs run more quickly on a computer than high level language programs 2 6 Text editors During the development of a high level language program after the analysis and design stages the programmer or team of programmers have to implement the design by coding it in a suitable high level language SOFTWARE DEVELOPMENT INT 2 COMPUTING 27 Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT Here is an example Visual BASIC program Private Sub btnOK_Click ByVal sender As System Object ByVal e As System EventArgs Handles btnOK Click coding for the OK command button displays an appropriate message for each possible number entered written by A Programmer on 21 09 07 Dim Number as Integer Number txtNumber text If Number 1 Then MsgBox Number amp wins you a colour TV If Number 2 Then MsgBox Number amp wins you a mobile phone If Number 3 Then MsgBox Number amp wins you a holiday in Spain If Number 4 Then MsgBox Number amp wins you 10p If Number 5 Then MsgBox Number amp wins you a day at the beach If Number lt 1 Then MsgBox Number am
137. ves technical information which is of little interest to most users except that it will usually include information about the specification of computer required including how much RAM it needs how fast a processor it must have and which operating system is required The technical guide should also include instructions on how to install the software Get hold of a software package that has been bought by your E Z school or college or one you have bought yourself at home ASG open it up and take a look inside the box that it came in Make a list of all the items of documentation that you find there 1 9 Evaluation The final stage in the process before the software can be distributed or sold is evaluation Evaluation involves reviewing the software under various headings to see if it of the quality required In this course we will review software under three headings fitness for purpose user interface and readability Is the software fit for purpose The answer is yes if the software does all the things that it is supposed to do under all reasonable conditions This means going back to the program specification produced at the analysis stage and checking that all the features of the software have been implemented It also means considering the results of testing and making sure that the program works correctly and is free from bugs The user interface should also be evaluated Is the program easy to use Is it clear what all
138. ways have an interpreter as well as the high level language program often called source code 2 5 Compilers An alternative approach is to use a compiler Going back to the Japanese lecture example instead of using a translator at the conference you could write down the text of your lecture in English and get a translator to translate it all into Japanese is advance You could then send the translated lecture script to the conference and have it read out by a Japanese person there The advantages are obvious your lecture can be delivered in the 1 hour allowed in the conference program and it can be used as often as required without it needing to be translated over and over again 26 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 LANGUAGES AND ENVIRONMENT A compiler program works in the same way It takes your high level language program and translates the whole program into machine code once This machine code can then be saved and kept Once translated it can be used over and over again without needing to be translated every time The compiled program therefore runs more quickly and the user doesn t need to have a translator program on their own computer Software that you buy such as a games program or an application will have been compiled into machine code before being distributed and sold What you get on the disk or CD is a machine code program that can run on yo
139. writing the previous value We need to have different variable names for each name and mark but we can t do that within the For Next loop The answer to our problem is a special type of data structure called an array An array can be sued for any number of items in this example we are assuming there are five students SOFTWARE DEVELOPMENT INT 2 COMPUTING 139 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING STANDARD ALGORITHMS Rather than setting up five variables we can set up a name array like for five names like this this Dim first_name As String Dim second_name As String Dim third_name As String Dim fourth_name As String Dim student_name 4 as String Dim fifth_name As String and rather than setting up another set of five variables for the marks like we can set up a mark array like this this Dim first_mark As Integer Dim second_mark As Integer Dim third_mark As Integer Dim mark 4 as Integer Dim fourth_mark As Integer Dim fifth_mark As Integer What does Dim student_name 4 as String mean Instead of setting up five separately named variables to hold the five names fourth_ fifth_name name Visual BASIC sets up a variable structure called an array that can store all five names with each array element being referred to by its index number 0 1 2 3 or 4 A UAC GY first_name second_ name student_ student_ student_
140. xtWide Text txtDeep Text txtCost Text txtTotalNumber Text txtTotalCost Text End Sub Test the new version of the program When you click the Clear button all the text boxes should clear ready to be used again 60 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 Jog HIGH LEVEL LANGUAGE PROGRAMMING GETTING STARTED 3 8 Arithmetical expressions In Section 3 7 the example program carried out two simple multiplications using the lines of code no_of_slabs wide deep total_cost no_of_slabs slab_cost All other calculations can be carried out in a similar way Some of the symbols used are the same as in normal arithmetic but some are different Adding Subtraction Multiplication Division Raising to a power 1 gt For complex calculations involving several operations multiplication and division take precedence over addition and subtraction However where the order of the operators matters it is safest to use brackets Here are some examples in Visual BASIC total first second third age 2009 birth_year time_in_australia time_in_scotland 12 tax salary 4600 0 23 years months 12 area_of_circle 3 14 radius 2 volume_of_sphere 4 3 14 radius 3 3 Note e the use of brackets where the order is important e the use of readable va
141. yed in the list box 100 SOFTWARE DEVELOPMENT INT 2 COMPUTING Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS Now test the program thoroughly using normal extreme and exceptional values for both message and how_many Modifications 3 At the moment this program can display any message over and over again but it is the same message on each line Can you adapt the program to produce displays like Go home Now Hint You will need two or three lines of code within the For Next loop Go home Now Go home O Now 2 4 9 Counting using For Next Each For Next loop that we have used so far is of the format For counter 1 to maximum Action Next Note that we have called the loop variable counter because that is what it does but it can be called anything you like The following versions would work in exactly the same way For silly name_for_a_variable 1 to maximum Action Next For i 1 to maximum Action Next The last of these using i as the loop variable is probably the most commonest SOFTWARE DEVELOPMENT INT 2 COMPUTING 101 Learning and Teaching Scotland 2009 HIGH LEVEL LANGUAGE PROGRAMMING BASIC CONSTRUCTS For Next loops are an is because the number of fixed in advance by the of maximum Example 4 9 1 Counting Program St

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