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User's Guide to the GNU C++ Library

1. x before 11 Bri sets the part of x to the left of Il to Bri setting x to Brillo N x before 2 sets z to the part of x to the left of x 2 or He in this case 60 User s Guide to the GNU C Class Library z x after Hel sets z to the part of x to the right of Hel or lo in this case N iT x through el sets z to the part of x up and including el or Hel in this case z x from el sets z to the part of x from el to the end or ello in this case x after Hel p sets x to Help x after 3 sets z to the part of x to the right of x 3 or o in this case N z abc z z after RXwhite sets z to the part of its old string to the right of the first group of whitespace setting z to ab c Use gsub below to strip out multiple occurrences of whitespace or any pattern x 0 J sets the first element of x to J x i returns a reference to the ith element of x or triggers an error if i is out of range common_prefix x Help returns the String containing the common prefix of the two Strings or Hel in this case common_suffix x to returns the String containing the common suffix of the two Strings or o in this case 17 5 Concatenation Z xtst y atC w y after w 1 sets z to Hello world x y sets x to Helloworld cat x y Z A faster way to say zZ X y cat z y X X Double concatenation faster
2. Chapter 17 The String class 55 17 The String class The String class is designed to extend GNU C to support string processing capabilities similar to those in languages like Awk The class provides facilities that ought to be convenient and efficient enough to be useful replacements for char based processing via the C string library i e strcpy strcmp etc in many applications Many details about String representations are described in the Representation section A separate SubString class supports substring extraction and modification operations This is implemented in a way that user programs never directly construct or represent substrings which are only used indirectly via String operations Another separate class Regex is also used indirectly via String operations in support of regular expression searching matching and the like The Regex class is based entirely on the GNU Emacs regex functions See section Syntax of Regular Expressions in GNU Emacs Manual for a full explanation of regular expression syntax For implementation details see the internal documentation in files regex h and regex c 17 1 Constructors Strings are initialized and assigned as in the following examples String x String y 0 Stringz Set x y and z to the nil string Note that either 0 or may always be used to refer to the nil string String x Hello String y Hello Set x and y to a copy of the st
3. a apply f applies function f to each element in a x a reduce f base accumulates the results of applying function f to successive elements of a starting with base a index int targ returns the index of the leftmost occurrence of the target or 1 if it does not occur a error char msg invokes the error handler The default version prints the error message then aborts 28 6 AVec operations AVecs provide additional arithmetic operations All vector by vector operators generate an error if the vectors are not the same length The following operations are provided for AVecs a b and base element scalar s a b Copies b to a a and b must be the same size a s fills all elements of a with the value s a is not resized at s a s a s a s adds subtracts multiplies or divides each element of a with the scalar at s a s art s a s adds subtracts multiplies or divides the scalar into a a b a b product a b quotient a b adds subtracts multiplies or divides corresponding elements of a and b a b a b a product b a quotient b adds subtracts multiplies or divides corresponding elements of b into a 100 User s Guide to the GNU C Class Library b returns the inner dot product of a and b sum returns the sum of elements of a sumsq returns the sum of squared elements of a minO returns the minimum element of a max0 returns the maximum element of a
4. if w sibling 0 traverse w sibling Chapter 26 List classes 89 26 List classes The files g include List hP and g include List ccP provide pseudo generic Lisp type List classes These lists are homogeneous lists more similar to lists in statically typed func tional languages like ML than Lisp but support operations very similar to those found in Lisp Any particular kind of list class may be generated via the genclass shell command However the implementation assumes that the base class supports an equality operator All equality tests use the operator and are thus equivalent to the use of equal not eq in Lisp All list nodes are created dynamically and managed via reference counts List variables are actually pointers to these list nodes Lists may also be traversed via Pixes as described in the section describing Pixes See Chapter 9 Pix page 35 Supported operations are mirrored closely after those in Lisp Generally operations with func tional forms are constructive functional operations while member forms often with the same name are sometimes procedural possibly destructive operations As with Lisp destructive operations are supported Programmers are allowed to change head and tail fields in any fashion creating circular structures and the like However again as with Lisp some operations implicitly assume that they are operating on pure lists and may enter infinite loops when pres
5. min_index returns the index of the minimum element of a max_index returns the index of the maximum element of a Note that it is possible to apply vector versions other arithmetic operators via the mapping functions For example to set vector b to the cosines of doubleVec a use b map cos a This is often more efficient than performing the operations in an element by element fashion Chapter 29 Plex classes 101 29 Plex classes A Plex is a kind of array with the following properties e Plexes may have arbitrary upper and lower index bounds For example a Plex may be declared to run from indices 10 10 e Plexes may be dynamically expanded at both the lower and upper bounds of the array in steps of one element e Only elements that have been specifically initialized or added may be accessed e Elements may be accessed via indices Indices are always checked for validity at run time Plexes may be traversed via simple variations of standard array indexing loops e Plex elements may be accessed and traversed via Pixes e Plex to Plex assignment and related operations on entire Plexes are supported e Plex classes contain methods to help programmers check the validity of indexing and pointer operations e Plexes form natural base classes for many restricted access data structures relying on logi cally contiguous indices such as array based stacks and queues e Plexes are implemented as pse
6. stdio h assert h A collection of constants defining the numbers of bits in builtin types minimum and maximum values and the like Most names are the same as those found in values h found on Sun systems A collection of common system calls and libc a functions Only those functions that can be declared without introducing new type definitions socket structures for exam ple are provided Common char functions like strcmp are among the declarations All functions are declared along with their library names so that they may be safely overloaded This file merely includes lt std h gt where string function prototypes are declared This is a workaround for the fact that system string h and strings h files often differ in contents This file merely includes lt std h gt where system function prototypes are declared This file merely includes lt std h gt where C library function prototypes are declared A collection of prototypes for functions usually found in libm a plus some defined constants that appear to be consistent with those provided in the AT amp T version The value of HUGE should be checked before using Declarations of all common math func tions are preceded with overload declarations since these are commonly overloaded Declaration of FILE _iobuf common macros like getc and function prototypes for libc a functions that operate on FILE s The va
7. acters as it does in this example Chapter 17 The String class 59 x matches r returns nonzero if String x as a whole matches Regex r int f x freq 1 returns the number of distinct nonoverlapping matches to the argument 2 in this case 17 4 Substring extraction Substrings may be extracted via the at before through from and after functions These behave as either lvalues or rvalues Z x at 2 3 sets String z to be equal to the length 3 substring of String x starting at zero based position 2 setting z to llo in this case A nil String is returned if the arguments don t make sense x at 2 2 r Sets what was in positions 2 to 3 of x to r setting x to Hero in this case As indicated here SubString assignments may be of different lengths x at He je x He is the substring of x that matches the first occurrence of it s argument The substitution sets x to jello If He did not occur the substring would be nil and the assignment would have no effect x at l 1 i replaces the rightmost occurrence of with i setting x to Helio Zz x at r sets String z to the first match in x of Regex r or ello in this case nil String is returned if there is no match z x before o sets z to the part of x to the left of the first occurrence of o or Hell in this case The argument may also be a String SubString or Regex If there is no match z is set to
8. the other relevant elements of class GetOpt are char optarg Used for communication from operator void to the caller When operator void finds an option that takes an argument the argument value is stored here int optind Index in argv of the next element to be scanned This is used for communication to and from the caller and for communication between successive calls to operator void When operator void returns EOF this is the index of the first of the non option elements that the caller should itself scan Otherwise optind communicates from one call to the next how much of argv has been scanned so far The libg version of GetOpt acts like standard UNIX getopt for the calling routine but it behaves differently for the user since it allows the user to intersperse the options with the other arguments As GetOpt works it permutes the elements of argv so that when it is done all the options precede everything else Thus all application programs are extended to handle flexible argument order Setting the environment variable POSIX OPTION ORDER disables permutation Then the behavior is completely standard Chapter 38 Projects and other things left to do 125 38 Projects and other things left to do 38 1 Coming Attractions Some things that will probably be available in libg in the near future e Revamped C compatibility header files that will be compatible with the forthcoming ANSI based GNU l
9. via something like include lt builtin h gt define lt T gt HASH x Chashpjw x name chars define DEFAULT_INITIAL_CAPACITY 1000 Since the hashpjw function from builtin h is appropriate here Changing the default capacity to a value expected to exceed the actual capacity helps to avoid hidden inefficiencies when a new VHMap is created without overriding the default which is all too easy to do Otherwise everything is the same as above substituting VHMap for AVLMap 30 User s Guide to the GNU C Class Library Chapter 7 Variable Sized Object Representation 31 7 Variable Sized Object Representation One of the first goals of the GNU C library is to enrich the kinds of basic classes that may be considered as nearly built into C A good deal of the inspiration for these efforts is derived from considering features of other type rich languages particularly Common Lisp and Scheme The general characteristics of most class and friend operators and functions supported by these classes has been heavily influenced by such languages Four of these types Strings Integers BitSets and BitStrings as well as associated and or derived classes require representations suitable for managing variable sized objects on the free store The basic technique used for all of these is the same although various details necessarily differ from class to class The general strategy for representing such objects is to
10. Contributors to GNU C library 11 Contributors to GNU C library Aside from Michael Tiemann who worked out the front end for GNU C and Richard Stallman who worked out the back end the following people not including those who have made their contributions to GNU CC should not go unmentioned e Doug Lea contributed most otherwise unattributed classes e Per Bothner contributed the iostream I O classes e Dirk Grunwald contributed the Random number generation classes and PairingHeaps e Kurt Baudendistel contributed Fixed precision reals e Doug Schmidt contributed ordered hash tables a perfect hash function generator and several other utilities e Marc Shapiro contributed the ideas and preliminary code for Plexes e Eric Newton contributed the curses window classes e Some of the I O code is derived from BSD 4 4 and was developed by the University of Cali fornia Berkeley e The code for converting accurately between floating point numbers and their string represen tations was written by David M Gay of AT amp T 12 User s Guide to the GNU C Class Library Chapter 1 Installing GNU C library 13 1 Installing GNU C library 1 Read through the README file and the Makefile Make sure that all paths system dependent compile switches and program names are correct 2 Check that files values h stdio h and math h declare and define values appropriate for your system 3 Type make
11. Integer atol char asciinumber int base 10 converts the base base char string into its Integer form void Integer printon ostream amp s int base 10 int width 0 prints the ascii string value of this as a base base number in field width at least width ostream lt lt x prints x in base ten format 66 User s Guide to the GNU C Class Library istream gt gt x reads x as a base ten number int compare Integer x Integer y returns a negative number if x lt y zero if x y or positive if x gt y int ucompare Integer x Integer y like compare but performs unsigned comparison add x y Z A faster way to say zZ X y sub x y Z A faster way to say Z X y mul x y Zz A faster way to sayz x y div x y Z A faster way to say z x y mod x y Z A faster way to say z x y and x y Z A faster way to say Z X amp y or x y Z A faster way to say z x y xor x y Z A faster way to say z x y lshift x y z A faster way to say z x lt lt y rshift x y z A faster way to say z x gt gt y pow x y Z A faster way to say z pow x y complement x z A faster way to say z x negate x z A faster way to say z x Chapter 19 The Rational Class 67 19 The Rational Class Class Rational provides multiple precision rational number arithmetic All rationals are main tained in simplest form i e with the numerator and den
12. You must make sure that they too receive or can get the source code If you link a program with the library you must provide complete object files to the recipients so that they can relink them with the library after making changes to the library and recompiling it And you must show them these terms so they know their rights 2 User s Guide to the GNU C Class Library Our method of protecting your rights has two steps 1 copyright the library and 2 offer you this license which gives you legal permission to copy distribute and or modify the library Also for each distributor s protection we want to make certain that everyone understands that there is no warranty for this free library If the library is modified by someone else and passed on we want its recipients to know that what they have is not the original version so that any problems introduced by others will not reflect on the original authors reputations Finally any free program is threatened constantly by software patents We wish to avoid the danger that companies distributing free software will individually obtain patent licenses thus in effect transforming the program into proprietary software To prevent this we have made it clear that any patent must be licensed for everyone s free use or not licensed at all Most GNU software including some libraries is covered by the ordinary GNU General Public License which was designed for utility programs This l
13. except that if the new size is smaller than the original than trailing elements are deleted and if greater trailing elements are uninitialized ali returns a reference to the i th element of a or produces an error if i is out of range a elem i returns a reference to the ith element of a Unlike the operator i is not checked to ensure that it is within range a returns true if a and b contain the same elements in the same order a b is the converse of a b 28 3 Constructive operations c concat a b sets c to the new vector constructed from all of the elements of a followed by all of b c map f a sets c to the new vector constructed by applying int function f int to each element of a c merge a b f sets c to the new vector constructed by merging the elements of ordered vectors a and b using ordering comparison function f c combine f a b sets c to the new vector constructed by applying int function f int int to successive pairs of a and b The result has length the shorter of a and b c reverse a sets c to a with elements in reverse order 28 4 Destructive operations a reverse reverses a in place Chapter 28 Vector classes 99 a sort f sorts a in place using comparison function f The sorting method is a variation of the quicksort functions supplied with GNU emacs a fi11 0 4 2 fills the 2 elements starting at a 4 with zero 28 5 Other operations
14. generators The RNG asLong member returns an unsigned long typically 32 bits of random bits Applications that require a number of random bits can use this directly More often these random bits are transformed to a uniform random number Return random bits converted to either a float or a double float asFloat double asDouble 3 using either asFloat or asDouble It is intended that asFloat and asDouble return differing precisions typically asDouble will draw two random longwords and transform them into a legal double while asFloat will draw a single longword and transform it into a legal float These members are used by subclasses of the Random class to implement a variety of random number distributions 80 User s Guide to the GNU C Class Library 23 2 ACG Class ACG is a variant of a Linear Congruential Generator Algorithm M described in Knuth Art of Computer Programming Vol III This result is permuted with a Fibonacci Additive Congruential Generator to get good independence between samples This is a very high quality random number generator although it requires a fair amount of memory for each instance of the generator The ACG ACG constructor takes two parameters the seed and the size The seed is any number to be used as an initial seed The performance of the generator depends on having a distribution of bits through the seed If you choose a number in the range of 0 to 31 a seed with more bits
15. a compiler might internally convert the statement into something like c a c b c a or perhaps something even more clever But since C does not know that Integer operator has any relation to Integer operator A C compiler cannot do this kind of expression optimization itself In many cases you can avoid construction of temporaries simply by using the assignment versions of operators whenever possible since these versions create no temporaries However for maximum flexibility most classes provide a set of embedded assembly code procedures that you can use to fully control time space and evaluation strategies Most of these procedures are three address procedures that take two const source arguments and a destination argument The procedures perform the appropriate actions placing the results in the destination which is may involve over writing old contents These procedures are designed to be fast and robust In particular aliasing is always handled correctly so that for example add x x x is perfectly OK The names of these procedures are listed along with the classes 34 User s Guide to the GNU C Class Library For example suppose you had an Integer expression a b a d c This would be compiled as if it were Integer ti b a Integer t2 d c Integer t3 t2 Integer t4 t1 t3 a t4 But with some manual cleverness you might yourself some up with sub a b a mul a d a div a c
16. also support backwards traversal via Pix i a last Set i to the last element of a or 0 if a is empty a prev i sets i to the previous element in a or 0 if there is none Collections supporting elements with an equality operation possess Pix j a seek x sets j to the index of the first occurrence of x or 0 if x is not contained in a Bag classes possess Pix j a seek x Pix from 0 sets j to the index of the next occurrence of x following i or 0 if x is not contained in a If i 0 the first occurrence is returned Set Bag and PQ classes possess Pix j a add x or a enq x for priority queues add x to the collection returning its Pix The Pix of an item can change in collections where further additions and deletions involve the actual movement of elements cur rently in OXPSet OXPBag XPPQ VOHSet but in all other cases an item s Pix may be considered a permanent key to its location Chapter 10 Header files for interfacing C to C 37 10 Header files for interfacing C to C The following files are provided so that C programmers may invoke common C library and system calls The names and contents of these files are subject to change in order to be compatible with the forthcoming GNU C library Other files not listed here are simply C compatible interfaces to corresponding C library files values h std h string h osfcn h libc h math h
17. are not accepted However pointers like this may be used by supplying the appropriate typedefs e g editing the resulting files to include typedef int intp The type name must be followed by one of the words val or ref to indicate whether the base elements should be passed to functions by value or by reference You can specify basic container classes using genclass base val ref proto where proto is the name of the class being generated Container classes like dictionaries and maps that require two types may be specified via genclass 2 keytype val ref basetype val ref proto where the key type is specified first and the contents type second The resulting classnames and filenames are generated by prepending the specified type names to the prototype names and separating the filename parts with dots For example genclass int val List generates class intList residing in files int List h and int List cc genclass 2 String ref int val VHMap generates the awkward but unavoidable class name StringintVHMap Of course programmers may use typedef or simple editing to create more appropriate names The existence of dot seperators in file names allows the use of GNU make to help automate configuration and recompilation An example Makefile exploiting such capabilities may be found in the libg proto kit directory 24 User s Guide to the GNU C Class Library The genclass utility operates via simple text substitution usin
18. create chunks of memory that include both header information e g the size of the object as well as the variable size data an array of some sort at the end of the chunk Generally the maximum size of an object is limited to something less than all of addressable memory as a safeguard The minimum size is also limited so as not to waste allocations expanding very small chunks Internally chunks are allocated in blocks well tuned to the performance of the new operator Class elements themselves are merely pointers to these chunks Most class operations are per formed via inline translation functions that perform the required operation on the corresponding representation However constructors and assignments operate by copying entire representations not just pointers No attempt is made to control temporary creation in expressions and functions involving these classes Users of previous versions of the classes will note the disappearance of both Tmp classes and reference counting These were dropped because while they did improve performance in some cases they obscure class mechanics lead programmers into the false belief that they need not worry about such things and occasionally have paradoxical behavior These variable sized object classes are integrated as well as possible into C Most such classes possess converters that allow automatic coercion both from and to builtin basic types e g char to and from String long i
19. denominator returns the denominator Integer floor x returns the greatest Integer less than x Integer ceil x returns the least Integer greater than x Integer trunc x returns the Integer part of x Integer round x returns the nearest Integer to x int compare x y User s Guide to the GNU C Class Library returns a negative zero or positive number signifying whether x is less than equal to or greater than y ostream lt lt x prints x in the form num den or just num if the denominator is one istream gt gt x reads x in the form num den or just num in which case the denominator is set to one add x y Z A faster way to say zZ X y sub x y Z A faster way to say Z X y mul x y Zz A faster way to sayz x y div x y Z A faster way to say z x y pow x y Z A faster way to say z pow x y negate x z A faster way to say z x Chapter 20 The Complex class 69 20 The Complex class Class Complex is implemented in a way similar to that described by Stroustrup In keeping with libg conventions the class is named Complex not complex Complex arithmetic and rela tional operators are provided Attempted division by 0 0 triggers an exception Complex numbers may be constructed and used in the following ways Complex x Declares an uninitialized Complex Complex x 2 Complex y 2 0 Set x and y to the
20. ene nee aner nett aner 90 26 3 heads and tails 00 ce rererere 90 26 4 Constructive operations 0 00 e cece cece rete ee eee 91 26 5 Destructive operations 0 0c ee eee ec ete ete ees 92 26 6 Other operations 0 00 c cee cece cee ravner 92 27 Linked Lists 0 cece cece eee eee ee 95 27 1 Doubly linked lists 0 0 2 ee eee eee 96 28 Vector classes aaannannuneunenenneneenenee 97 28 1 Constructors and assignment 00 cece eee eee ee nee 97 28 2 Status and access 00 cece cee cece cee tenn renn 97 28 3 Constructive operations 0 0 cece eee eee cee e ee eee 98 28 4 Destructive operations 0 e cece ee cee teen ees 98 28 5 Other operations 0 00 e cee cece cee ene e ee 99 28 6 AVec operations 0 0 c cee eee ee cee cette ete e ee eee 99 29 Plex classes 0 cece cece ee 101 30 Stacks 0 ec cc cee eee eee neeneees 107 ili 31 32 33 34 35 36 37 38 User s Guide to the GNU C Class Library Queues ranvuuuuuununuvnenernenenerneneneer 109 Double ended Queues eee e eee 111 Priority Queue class prototypes 113 Set class prototypes 0 c ccc e cece eee 115 Bag class prototypes sees eee eee 119 Map Class Prototypes 0 cece eee 121 C version of the GNU getopt function 123 Projects and other things
21. from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns Each version is given a distinguishing version number If the Library specifies a version number of this License which applies to it and any later version you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation If the Library does not specify a license version number you may choose any version ever published by the Free Software Foundation If you wish to incorporate parts of the Library into other free programs whose distribution conditions are incompatible with these write to the author to ask for permission For software which is copyrighted by the Free Software Foundation write to the Free Software Foundation we sometimes make exceptions for this Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally NO WARRANTY BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE THERE IS NO WAR RANTY FOR THE LIBRARY TO THE EXTENT PERMITTED BY APPLICABLE LAW EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND OR OTHER PARTIES PROVIDE THE LIBRARY AS IS WITHOUT WARRANTY OF ANY KIND EITHER EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHAN
22. is chosen Other values are deterministically modified to give a better distribution of bits This provides a good random number generator while still allowing a sequence to be repeated given the same initial seed The size parameter determines the size of two tables used in the generator The first table is used in the Additive Generator see the algorithm in Knuth for more information In general this table is size longwords long The default value used in the algorithm in Knuth gives a table of 220 bytes The table size affects the period of the generators smaller values give shorter periods and larger tables give longer periods The smallest table size is 7 longwords and the longest is 98 longwords The size parameter also determines the size of the table used for the Linear Congruential Generator This value is chosen implicitly based on the size of the Additive Congruential Generator table It is two powers of two larger than the power of two that is larger than size For example if size is 7 the ACG table is 7 longwords and the LCG table is 128 longwords Thus the default size 55 requires 55 256 longwords or 1244 bytes The largest table requires 2440 bytes and the smallest table requires 100 bytes Applications that require a large number of generators or applications that aren t so fussy about the quality of the generator may elect to use the MLCG generator 23 3 MLCG The MLCG class implements a Multiplicative Linear Congruent
23. is in a a ind returns a reference to the item indexed by ind ind a first returns the Pix of first item in the set or 0 if the Set is empty For ordered Sets this is the Pix of the least element a next ind advances ind to the Pix of next element or 0 if there are no more ind a seek x Sets ind to the Pix of x or 0 if x is not in a returns true if a and b contain all the same elements v 1 WW returns true if a and b do not contain all the same elements v n Chapter 34 Set class prototypes a lt b returns true if a is a subset of b al b Adds all elements of b to a a Deletes all elements of b from a a amp b Deletes all elements of a not occurring in b 117 118 User s Guide to the GNU C Class Library Chapter 35 Bag class prototypes 119 35 Bag class prototypes Bag classes maintain unbounded collections of items potentially containing duplicate elements These are currently implemented in several ways differing in representation strategy algorithmic efficiency and appropriateness for various tasks Listed next to each are average followed by worst case if different time complexities for a adding f finding via seek contains d deleting elements ay OG fd Om f O log n d OG SLBags implement unordered Bags via linked lists a O 1 f O n d O a OSLBags implement ordered Bags via linked lists a O n f O n d O n XPBags implement
24. is set to zero Chapter 21 Fixed precision numbers 71 21 Fixed precision numbers Classes Fix16 Fix24 Fix32 and Fix48 support operations on 16 24 32 or 48 bit quantities that are considered as real numbers in the range 1 1 Such numbers are often encountered in digital signal processing applications The classes may be be used in isolation or together Class Fix32 operations are entirely self contained Class Fix16 operations are self contained except that the multiplication operation Fix16 Fix16 returns a Fix32 Fix24 and Fix48 are similarly related The standard arithmetic and relational operations are supported lt lt gt gt lt lt gt gt lt lt gt gt All operations include provisions for special handling in cases where the result exceeds 1 0 There are two cases that may be handled separately overflow where the results of addition and subtraction operations go out of range and all other range errors in which resulting values go off scale as with division operations and assignment or initialization with off scale values In signal processing applications it is often useful to handle these two cases differently Handlers take one argument a reference to the integer mantissa of the offending value which may then be manipulated In cases of overflow this value is the result of the integer arithmetic computation on the mantissa in others it is
25. it is not allowed This is the first released version of the library GPL It is numbered 2 because it goes with version 2 of the ordinary GPL Preamble The licenses for most software are designed to take away your freedom to share and change it By contrast the GNU General Public Licenses are intended to guarantee your freedom to share and change free software to make sure the software is free for all its users This license the Library General Public License applies to some specially designated Free Software Foundation software and to any other libraries whose authors decide to use it You can use it for your libraries too When we speak of free software we are referring to freedom not price Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software and charge for this service if you wish that you receive source code or can get it if you want it that you can change the software or use pieces of it in new free programs and that you know you can do these things To protect your rights we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights These restrictions translate to certain responsibilities for you if you distribute copies of the library or if you modify it For example if you distribute copies of the library whether gratis or for a fee you must give the recipients all the rights that we gave you
26. left to do 125 38 1 Coming Attractions 00 0 0 cece ccc ete eee e ene n eens 125 38 2 Wish List 2 0 0 cece cece cece cece terre errr rr rrr rrr rrr 125 38 3 How to contribute 0 ec serere rererere rererere 125
27. r e a z o Regex r2 a z char C int i pos len double f String words 10 words 0 a words 1 b words 2 c 17 3 Comparing Searching and Matching The usual lexicographic relational operators lt lt gt gt are defined A functional form compare String String is also provided as is fcompare String String which com pares Strings without regard for upper vs lower case All other matching and searching operations are based on some form of the non public match and search functions match and search differ in that match attempts to match only at the given starting position while search starts at the position and then proceeds left or right looking for a match As seen in the following examples the second optional startpos argument to functions 58 User s Guide to the GNU C Class Library using match and search specifies the starting position of the search If non negative it results in a left to right search starting at position startpos and if negative a right to left search starting at position x length startpos In all cases the index returned is that of the beginning of the match or 1 if there is no match Three String functions serve as front ends to search and match index performs a search re turning the index matches performs a match returning nonzero actually the length of the match on success and contains is a boolean function performing eit
28. replicated bit of a a atoBitSet ababX a b X converts the char string into a bitset with a denoting false b denoting true and X denoting infinite replication a printon cout 0 prints a to cout represented with for falses for trues and no replication marker cout lt lt prints a to cout representing lases by f trues by t and using as the repli cation marker 22 2 BitString BitStrings are objects that contain arbitrary length strings of zeroes and ones BitStrings possess some features that make them behave like sets and others that behave as strings They are useful in applications such as signature based algorithms where both capabilities are needed Representational details are discussed in the Representation chapter Most capabilities are exact analogs of those supported in the BitSet and String classes A BitSubString is used with substring operations along the same lines as the String SubString class A BitPattern class is used for masked bit pattern searching Only a default constructor is supported The declaration BitString a initializes a to be an empty BitString BitStrings may often be initialized via atoBitString and longtoBitString Set operations complement amp amp behave just as the BitSet versions except that there is no virtual bit complementing complements only those bits i
29. the forest approach Keith Gorlen s OOPS library adopts the hierarchical approach and may be an attractive alternative for C programmers who prefer this style Currently and or in the near future libg provides support for a few basic kinds of classes The first kind of support provides an interface between C programs and C libraries This includes basic header files like stdio h as well as things like the File and stream classes Other 18 User s Guide to the GNU C Class Library classes that interface to other aspects of C libraries like those that maintain environmental infor mation are in various stages of development all will undergo implementation modifications when the forthcoming GNU libe library is released The second kind of support contains general purpose basic classes that transparently manage variable sized objects on the freestore This includes Obstacks multiple precision Integers and Rationals arbitrary length Strings BitSets and BitStrings Third several classes and utilities of common interest e g Complex numbers are provided Fourth a set of pseudo generic prototype files are available as a mechanism for generating common container classes These are described in more detail in the introduction to container prototypes Currently only a textual substitution mechanism is available for generic class creation Chapter 4 GNU C library stylistic conventions 19 4 GNU C library sty
30. the file and then deletes it if possible by calling the system function to delete the file with the name provided in the nm field 14 2 Basic IO e read and write perform binary IO via stdio fread and fwrite e get and put for chars invoke stdio getc and pute macros e put const char s outputs a null terminated string via stdio fputs e unget and putback are synonyms Both call stdio ungetc 14 3 File Control flush seek tell and tell call the corresponding stdio functions flush char and fill call stdio _flsbuf and _filbuf respectively setbuf is mainly useful to turn off buffering in cases where nonsequential binary IO is being per formed raw is a synonym for setbuf _IONBF After a f raw using the stdio functions instead of the system read write etc calls entails very little overhead Moreover these become fully compatible with intermixed system calls e g lseek f filedesc 0 0 While intermixing File and system IO calls is not at all recommended this technique does allow the File class to be used in conjunction with other functions and libraries already set up to operate on file descriptors setbuf should be called at most once after a constructor or open but before any IO 14 4 File Status File status is maintained in several ways A File may be checked for accessibility via is_open which returns true if the File is bound to a usable physical file readable which returns true if the File can be rea
31. the mean The remaining members allow you to inspect and change the mean 23 10 Normal The Normalclass implements the normal distribution The first parameter to the constructor mean is the mean and the second variance is the variance The remaining members allow you to inspect and change the mean and variance The LogNormal class is a subclass of Normal 23 11 LogNormal The LogNormalclass implements the logarithmic normal distribution The first parameter to the constructor mean is the mean and the second variance is the variance The remaining members allow you to inspect and change the mean and variance The LogNormal class is a subclass of Normal 23 12 Poisson The Poisson class implements the poisson distribution The first parameter to the constructor is the mean The remaining members allow you to inspect and change the mean Chapter 23 Random Number Generators and related classes 83 23 13 DiscreteUniform The DiscreteUniform class implements a uniform random variable over the closed interval ranging from low high The first parameter to the constructor is Low and the second is high although the order of these may be reversed The remaining members allow you to inspect and change low and high 23 14 Uniform The Uniform class implements a uniform random variable over the open interval ranging from low high The first parameter to the constructor is low and the second is high although the order of th
32. unordered Bags via XPlexes a O 1 OXPBags implement ordered Bags via XPlexes a O n ra SplayBags implement ordered Bags via Sleator and Tarjan s JACM 1985 splay trees The al gorithms use a version of simple top down splaying described on page 669 of the article Amortized a O log n f O log n d O log n VHBags implement unordered Bags via hash tables The tables are automatically resized when their capacity is exhausted a O 1 O n f O 1 O n d O 1 O n CHBags implement unordered Bags via chained hash tables fa O 1 O n f O 1 O n d O 1 O n The implementations differ in whether their constructors require an argument to specify their initial capacity Initial capacities are required for plex and hash table based Bags If none is given DEFAULT_INITIAL_CAPACITY from lt T gt defs h is used Bags support the following operations for some class Bag instances a and b Pix ind and base element x Since all implementations are virtual derived classes of the lt T gt Bag class it is possible to mix and match operations across different implementations although as usual operations are generally faster when the particular classes are specified in functions operating on Bags Pix based operations are more fully described in the section on Pixes See Chapter 9 Pix page 35 Bag a or Bag a int initial size Declares a to be an empty Bag The second version is allowed in
33. work containing the Library or a portion of it either verbatim or with modifications and or translated straightforwardly into another language Hereinafter translation is included without limitation in the term modification Source code for a work means the preferred form of the work for making modifications to it For a library complete source code means all the source code for all modules it contains plus any associated interface definition files plus the scripts used to control compilation and installation of the library Activities other than copying distribution and modification are not covered by this License they are outside its scope The act of running a program using the Library is not restricted and output from such a program is covered only if its contents constitute a work based on the Library independent of the use of the Library in a tool for writing it Whether that is true depends on what the Library does and what the program that uses the Library does 1 You may copy and distribute verbatim copies of the Library s complete source code as you receive it in any medium provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty keep intact all the notices that refer to this License and to the absence of any warranty and distribute a copy of this License along with the Library User s Guide to the GNU C Class Library You ma
34. Bag classes that require initial capacity or sizing specifications 120 User s Guide to the GNU C Class Library a empty returns true if a is empty a length returns the number of elements in a ind a add x inserts x into a returning its index del x deletes one occurrence of x from a v a remove x deletes all occurrences of x from a clear v deletes all elements from a a contains x returns true if x is in a a nof x returns the number of occurrences of x in a a ind returns a reference to the item indexed by ind int a first returns the Pix of first item in the Bag or 0 if the Bag is empty For ordered Bags this is the Pix of the least element a next ind advances ind to the Pix of next element or 0 if there are no more ind a seek x Pix from 0 Sets ind to the Pix of the next occurrence x or 0 if there are none If from is 0 the first occurrence is returned else the following from Chapter 36 Map Class Prototypes 121 36 Map Class Prototypes Maps support associative array operations insertion deletion and membership of records based on an associated key They require the specification of two types the key type and the contents type These are currently implemented in several ways differing in representation strategy algorithmic efficiency and appropriateness for various tasks Listed next to each are average followed by worst case if diffe
35. BitSet a declares an empty BitSet BitSet a atoBitSet 001000 sets a to the BitSet 0010 reading left to right The 0 indicates that the set ends with an infinite number of zero clear bits BitSet a atoBitSet 00101 sets a to the BitSet 00101 where 1 means that the set ends with an infinite number of one set bits BitSet a longtoBitSet long 23 sets a to the BitSet 111010 the binary representation of decimal 23 BitSet a utoBitSet unsigned 23 sets a to the BitSet 111010 the binary representation of decimal 23 The following functions and operators are provided Assume the declaration of BitSets a 0011010 b 101101 throughout as examples a returns the complement of a or 1100101 in this case a complement sets a to a a amp b a amp b returns a intersected with b or 0011010 alb al b returns a unioned with b or 1011111 a b a b returns the set difference of a and b or 000010 a b a b returns the symmetric difference of a and b or 1000101 a empty returns true if a is an empty set Chapter 22 Classes for Bit manipulation 75 a b returns true if a and b contain the same set a lt b returns true if a is a subset of b a lt b returns true if a is a proper subset of b al b a gt b a gt b are the converses of the above a set 7 sets the 7th counting from 0 bit of a setting a to 001111010 a clear 2 clears the 2nd bit bi
36. Complex value 2 0 0 0 Complex x 2 3 Sets x to the Complex value 2 3 Complex u x Complex v x Set u and v to the same value as x double real Complex amp x returns the real part of x double imag Complex amp x returns the imaginary part of x double abs Complex amp x returns the magnitude of x double norm Complex amp x returns the square of the magnitude of x double arg Complex amp x returns the argument amplitude of x Complex polar double r double t 0 0 returns a Complex with abs of r and arg of t Complex conj Complex amp x returns the complex conjugate of x Complex cos Complex amp x returns the complex cosine of x Complex sin Complex amp x returns the complex sine of x 70 User s Guide to the GNU C Class Library Complex cosh Complex amp x returns the complex hyperbolic cosine of x Complex sinh Complex amp x returns the complex hyperbolic sine of x Complex exp Complex amp x returns the exponential of x Complex log Complex amp x returns the natural log of x Complex pow Complex amp x long p returns x raised to the p power Complex pow Complex amp x Complex amp p returns x raised to the p power Complex sqrt Complex amp x returns the square root of x ostream lt lt x prints x in the form re im istream gt gt x reads x in the form re im or just re or re in which case the imaginary part
37. Plex j p add_low x j p add high x Extend the Plex by one element downward upward The new minimum maximum index is returned j p del_low j p del_high Shrink the Plex by one element on the low high end The new minimum maximum element is returned An exception occurs if the Plex is empty p append q Append all of Plex q to the high side of p p prepend q Prepend all of q to the low side of p p clear Delete all elements resetting p to a zero sized Plex p reset_low i Resets p to be indexed starting at low i For example if p were initially declared via Plex p 0 10 0 and then re indexed via p reset_low 5 it could then be indexed from indices 5 14 p fill x sets all p i to x p fill x lo hi sets all of pfi from lo to hi inclusive to x p reverse reverses p in place p chunk size returns the chunk size used for the plex p error const char msg calls the resettable error handler MPlexes are plexes with bitmaps that allow items to be logically deleted and restored They behave like other plexes but also support the following additional and modified capabilities Chapter 29 Plex classes 105 p del index i p del_Pix pix logically deletes p i p pix After deletion attempts to access p i generate a error Indexing via low high prev and next skip the element Deleting an element never changes the logical bounds of the plex p undel_inde
38. Public License has appeared then you can specify that version instead if you wish Do not make any other change in these notices GNU LIBRARY GENERAL PUBLIC LICENSE 5 Once this change is made in a given copy it is irreversible for that copy so the ordinary GNU General Public License applies to all subsequent copies and derivative works made from that copy This option is useful when you wish to copy part of the code of the Library into a program that is not a library 4 You may copy and distribute the Library or a portion or derivative of it under Section 2 in object code or executable form under the terms of Sections 1 and 2 above provided that you accompany it with the complete corresponding machine readable source code which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange If distribution of object code is made by offering access to copy from a designated place then offering equivalent access to copy the source code from the same place satisfies the requirement to distribute the source code even though third parties are not compelled to copy the source along with the object code 5 A program that contains no derivative of any portion of the Library but is designed to work with the Library by being compiled or linked with it is called a work that uses the Library Such a work in isolation is not a derivative work of the Library and therefore fal
39. TABILITY AND FITNESS FOR A PARTICULAR PURPOSE THE ENTIRE RISK AS TO THE QUALITY AND PERFOR MANCE OF THE LIBRARY IS WITH YOU SHOULD THE LIBRARY PROVE DEFEC TIVE YOU ASSUME THE COST OF ALL NECESSARY SERVICING REPAIR OR COR RECTION IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRIT ING WILL ANY COPYRIGHT HOLDER OR ANY OTHER PARTY WHO MAY MODIFY AND OR REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE BE LIABLE TO YOU FOR DAMAGES INCLUDING ANY GENERAL SPECIAL INCIDENTAL OR CON SEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE LIBRARY INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING REN DERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE EVEN GNU LIBRARY GENERAL PUBLIC LICENSE 9 IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES END OF TERMS AND CONDITIONS 10 User s Guide to the GNU C Class Library How to Apply These Terms to Your New Libraries If you develop a new library and you want it to be of the greatest possible use to the public we recommend making it free software that everyone can redistribute and change You can do so by permitting redistribution under these terms or alternatively under the terms of the ordinary General Public License To apply these terms attach the following notices to the library It is safest to attach them to the start of each source file to m
40. User s Guide to the GNU C Library last updated April 29 1992 for version 2 0 Doug Lea dleg oswego edu Copyright 1988 1991 1992 Free Software Foundation Inc Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies Permission is granted to copy and distribute modified versions of this manual under the condi tions for verbatim copying provided also that the section entitled GNU Library General Public License is included exactly as in the original and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one Permission is granted to copy and distribute translations of this manual into another language under the above conditions for modified versions except that the section entitled GNU Library General Public License may be included in a translation approved by the author instead of in the original English Note The GNU C library is still in test release You will be performing a valuable service if you report any bugs you encounter GNU LIBRARY GENERAL PUBLIC LICENSE 1 GNU LIBRARY GENERAL PUBLIC LICENSE Version 2 June 1991 Copyright 1991 Free Software Foundation Inc 59 Temple Place Suite 330 Boston MA 02111 1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing
41. a A related phenomenon occurs when creating your own constructive functions returning instances of such types Suppose you wanted to write function Integer f const Integer amp a Integer r a r a returnr This function when called asin a f a demonstrates a similar kind of wasted copy The returned value r must be copied out of the function before it can be used by the caller In GNU C there is an alternative via the use of named return values Named return values allow you to manipulate the returned object directly rather than requiring you to create a local inside a function and then copy it out as the returned value In this example this can be done via Integer f const Integer amp a return r a r a return A final guideline The overloaded operators are very convenient and much clearer to use than procedural code It is almost always a good idea to make it right then make it fast by translating expression code into procedural code after it is known to be correct Chapter 9 Pseudo indexes 35 9 Pseudo indexes Many useful classes operate as containers of elements Techniques for accessing these elements from a container differ from class to class In the GNU C library access methods have been partially standardized across different classes via the use of pseudo indexes called Pixes A Pix acts in some ways like an index and in some ways like a pointer Their underlying representations are just void poi
42. a omitting all occurrences of x remove f a setq b remove if f a Sets b to a copy of a omitting values causing function f to return true select f a setq b remove if not f a Sets b to a copy of a omitting values causing function f to return false merge a b f setq c merge a b f Sets c to a list containing the ordered elements using the comparison function f of the sorted lists a and b 92 User s Guide to the GNU C Class Library 26 5 Destructive operations a append b rplacd last a b appends b to the end of a No new nodes are constructed a prepend b setq a append b a prepends b to the beginning of a a del x delete xa deletes all nodes with value x from a a del f delete if f a deletes all nodes causing function f to return true a select f delete if not f a deletes all nodes causing function f to return false a reverse nreverse a reverses a in place a sort f sort a f sorts a in place using ordering comparison function f a apply f mapc f a Applies void function f int x to each element of a a subst int old int repl subst repl old a substitutes repl for each occurrence of old in a Note the different argument order than the Lisp version 26 6 Other operations a find int x find xa returns the intList at the first occurrence of x a find b findb a returns the intList at t
43. a fully saturated i e most positive or most negative value Handling may be reset to any of several provided functions or any other user defined function via set_overflow_handler and set_range_error_handler The provided functions for Fix16 are as follows corresponding functions are also supported for the others Fix16_overflow_saturate The default overflow handler Results are saturated positive results are set to the largest representable value binary 0 111111 and negative values to 1 0 Fixi6_ignore Performs no action For overflow this will allow addition and subtraction operations to wrap around in the same manner as integer arithmetic and for saturation will leave values saturated Fixi6_overflow_warning_saturate Prints a warning message on standard error then saturates the results Fix16 warning The default range_error handler Prints a warning message on standard error otherwise leaving the argument unmodified Fix16 abort prints an error message on standard error then aborts execution In addition to arithmetic operations the following are provided 72 User s Guide to the GNU C Class Library Fix16 a 0 5 Constructs fixed precision objects from double precision values Attempting to initialize to a value outside the range invokes the range_error handler except as a convenience initialization to 1 0 sets the variable to the most positive representable value binary 0 1111111 withou
44. ace allocated via new char some_size The entries are used cyclicly The size n of the ring is fixed at construction After that every nth use of the ring will reuse or reallocate the same space AllocRings are needed in order to temporarily hold chunks of space that are needed transiently but across constructor destructor scopes They mainly useful for storing strings containing formatted characters to print across various functions and coercions These strings are needed across routines so may not be deleted in any one of them but should be recovered at some point In other words an AllocRing is an extremely simple minded garbage collection mechanism The GNU C library used to use one AllocRing for such formatting purposes but it is being phased out and is now only used by obsolete functions These days AllocRings are probably not very useful Support includes AllocRing a int n constructs an Alloc ring with n entries all null void mem a alloc sz moves the ring pointer to the next entry and reuses the space if their is enough also allocates space via new char sz int present a contains void ptr returns true if ptr is held in one of the ring entries a clear deletes all space pointed to in any entry This is called automatically upon destruction a free void ptr If ptr is one of the entries calls delete of the pointer and resets to entry pointer to null 54 User s Guide to the GNU C Class Library
45. additional decision Should the Map member functions like m contains p take arguments p by reference i e typed as int Map contains const Person amp p or by value i e typed as int Map contains const Person p Generally for user defined classes you want to pass by reference and for builtins and pointers to pass by value SO you should pick by reference 28 User s Guide to the GNU C Class Library You can now create Person defs h via genclass Person ref defs This creates a simple skeleton that you must edit First add include Person h to the top Second edit the lt T gt CMP a b macro to compare on name via define lt T gt CMP a b compare a name b name which invokes the int compare const String amp const String amp function from String h Of course you could define this in any other way as well In fact the default versions in the skeleton turn out to be OK albeit inefficient in this particular example You may also want to create file SSN defs h Here choosing call by value makes sense and since no other capabilities like comparison functions of the SSNs are used and the defaults are OK anyway you d type genclass SSN val defs and then edit to place include SSN h at the top Finally you can generate the classes First generate the base class for Maps via genclass 2 Person ref SSN val Map This generates only the abstract class not the implementation
46. ake a chunk size argument SLStack constructors take no argument Assume the declaration of a base element x Stack s or Stack s int capacity declares a Stack u empty 0 returns true if stack s is empty s full returns true if stack s is full XPStacks and SLStacks never become full s length returns the current number of elements in the stack s push x pushes x on stack s p s pop pops and returns the top of stack s top returns a reference to the top of stack s del top pops but does not return the top of stack When large items are held on the stack it is often a good idea to use top to inspect and use the top of stack followed by a del top s clear removes all elements from the stack 108 User s Guide to the GNU C Class Library Chapter 31 Queues 109 31 Queues Queues are declared as an abstract class They are currently implemented in any of three ways VQueue implement fixed sized Queues via arrays XPQueue implement dynamically sized Queues via XPlexes SLQueue implement dynamically size Queues via linked lists All possess the same capabilities they differ only in constructors VQueue constructors require a fixed maximum capacity argument XPQueue constructors optionally take a chunk size argument SLQueue constructors take no argument Assume the declaration of a base element x Queue q or Queue q int capacity declares a queue q empty retu
47. all to compile the library test and install Current details about contents of the tests and utilities are in the README file 14 User s Guide to the GNU C Class Library Chapter 2 Trouble in Installation 15 2 Trouble in Installation Here are some of the things that have caused trouble for people installing GNU C library 1 Make sure that your GNU C version number is at least as high as your libg version number For example libg 1 22 0 requires g 1 22 0 or later releases 2 Double check system constants in the header files mentioned above 16 User s Guide to the GNU C Class Library Chapter 3 GNU C library aims objectives and limitations 17 3 GNU C library aims objectives and limitations The GNU C library libg is an attempt to provide a variety of C programming tools and other support to GNU C programmers Differences in distribution policy are only part of the difference between libg a and AT amp T libC a libg is not intended to be an exact clone of libC For one libg contains bits of code that depend on special features of GNU g that are either different or lacking in the AT amp T version including slightly different inlining and overloading strategies dynamic local arrays etc All of these differences are minor For example while the AT amp T and GNU stream classes are implemented in very different ways the vast majority of C programs compile and run under eith
48. an move while it is growing Once it has been finished it never changes address again So the top of the stack is typically an immature growing object while the rest of the stack is of mature fixed size and fixed address objects These routines grab large chunks of memory using the GNU C new operator On occasion they free chunks via delete Each independent stack is represented by a Obstack One motivation for this package is the problem of growing char strings in symbol tables Unless you are a fascist pig with a read only mind Gosper s immortal quote from HAKMEM item 154 out of context you would not like to put any arbitrary upper limit on the length of your symbols In practice this often means you will build many short symbols and a few long symbols At the time you are reading a symbol you don t know how long it is One traditional method is to read a symbol into a buffer realloc ating the buffer every time you try to read a symbol that is longer than the buffer This is beaut but you still will want to copy the symbol from the buffer to a more permanent symbol table entry say about half the time With obstacks you can work differently Use one obstack for all symbol names As you read a symbol grow the name in the obstack gradually When the name is complete finalize it Then if the symbol exists already free the newly read name The way we do this is to take a large chunk allocating memory from l
49. ar 26 3 heads and tails a get ORa head car a returns a reference to the head field a 2 elt a 2 returns a reference to the second counting from zero head field a tail cdr a returns the intList that is the tail of a a last last a returns the intList that is the last node of a a nth 2 ntha 2 returns the intList that is the nth node of a Chapter 26 List classes 91 a set_tail b rplacd a b sets a s tail to b a push 2 push 2 a equivalent to a intList 2 a int x a pop setq x car a pop a returns the head of a also setting a to its tail 26 4 Constructive operations a Oo iT Oo iT Oo iT a Oo iT a Oo iT c copy a setq b copy seq a sets b to a copy of a reverse a setq b reverse a Sets b to a reversed copy of a concat a b setq c concat ab Sets c to a concatenated copy of a and b append a b setq c append a b Sets c to a concatenated copy of a and b All nodes of a are copied with the last node pointing to b map f a setq b mapcar f a Sets b to a new list created by applying function f to each node of a combine f a b Sets c to a new list created by applying function f to successive pairs of a and b The resulting list has length the shorter of a and b remove x a setq b remove x a Sets b to a copy of
50. are internally dynamically managed to maintain proper length This means that for example BitStrings are concatenatable while BitSets and Integers are not e BitSet32 and BitSet256 have precisely the same properties as BitSets except that they use constant fixed length bit vectors e While all classes support basic unary and binary operations amp the semantics differ BitSets perform bit operations that precisely mirror those for infinite sets For example com plementing an empty BitSet returns one representing an infinite number of set bits Operations on BitStrings and Integers operate only on those bits actually present in the representation For BitStrings and Integers the the amp operation returns a BitString with a length equal to the minimum length of the operands and return one with length of the maximum e Only BitStrings support substring extraction and bit pattern matching 22 1 BitSet BitSets are objects that contain logically infinite sets of nonnegative integers Representational details are discussed in the Representation chapter Because they are logically infinite all BitSets 74 User s Guide to the GNU C Class Library possess a trailing infinitely replicated 0 or 1 bit called the virtual bit and indicated via 0 or 1 BitSet32 and BitSet256 have they same properties except they are of fixed length and thus have no virtual bit BitSets may be constructed as follows
51. ary File functions indicate IO success status or failure solely through the state not via return values of the functions The void operator or rdstate may be used to test success In particular according to c conversion rules the void coercion is automatically applied whenever the File amp return value of any File function is tested in an if or while Thus 48 User s Guide to the GNU C Class Library for example an easy way to copy all of stdin to stdout until eof at which point get fails or some error is char c while cin get c amp amp cout put c The current version of istreams and ostreams differs significantly from previous versions in order to obtain compatibility with AT amp T 1 2 streams Most code using previous versions should still work However the following features of File are not incorporated in streams they are still present in File scan const char fmt remove read write setbuf raw Additionally the feature of previous streams that allowed free intermixing of stream and stdio input and output is no longer guaranteed to always behave as desired Chapter 15 The Obstack class 49 15 The Obstack class The Obstack class is a simple rewrite of the C obstack macros and functions provided in the GNU CC compiler source distribution Obstacks provide a simple method of creating and maintaining a string table optimized for the very frequent task of building strings character by charac
52. aster way to say z or x y Z A faster way to say z xor x y Z A faster way to say z lshift x y z A faster way to say z rshift x y z A faster way to say z complement x z A faster way to say z x y x amp y x ly xX lt lt y x gt gt y Chapter 23 Random Number Generators and related classes 79 23 Random Number Generators and related classes The two classes RNG and Random are used together to generate a variety of random number distributions A distinction must be made between random number generators implemented by class RNG and random number distributions A random number generator produces a series of randomly ordered bits These bits can be used directly or cast to other representations such as a floating point value A random number generator should produce a uniform distribution A random number distribution on the other hand uses the randomly generated bits of a generator to produce numbers from a distribution with specific properties Each instance of Random uses an instance of class RNG to provide the raw uniform distribution used to produce the specific distribution Several instances of Random classes can share the same instance of RNG or each instance can use its own copy 23 1 RNG Random distributions are constructed from members of class RNG the actual random number generators The RNG class contains no data it only serves to define the interface to random number
53. ate may be modified via clear flag which despite its name sets the corresponding state_value flag clear with no arguments resets the state to good failif int cond sets the state to _fail only if cond is true Errors occuring during constructors and file opens also invoke the function error error in turn calls a resetable error handling function pointed to by the non member global variable File_ error_handler only if a system error has been generated Since error cannot tell if the current system error is actually responsible for a failure it may at times print out spurious messages Three error handlers are provided The default verbose_File_error_handler calls the system function perror to print the corresponding error message on standard error and then returns to the caller quiet_File_error_handler does nothing and simply returns fatal_File_error_ handler prints the error and then aborts execution These three handlers or any other user defined error handlers can be selected via the non member function set_File_error_handler All read and write operations communicate either logical or physical failure by setting the fail flag All further operations are blocked if the state is in a _fail or_bad condition Programmers must explicitly use clear to reset the state in order to continue IO processing after either a logical or physical failure C programmers who are unfamiliar with these conventions should note that unlike the stdio libr
54. ble with raw system file reads and writes like the system read and lseek calls when buffering is disabled see below The FILE stdio file pointer is however maintained as protected Classes derived from File may only use the IO operations provided by File which encompass essentially all stdio capabilities The class contains four general kinds of functions methods for binding Files to physical Unix files basic IO methods file and buffer control methods and methods for maintaining logical and physical file status Binding and related tasks are accomplished via File constructors and destructors and member functions open close remove filedesc name setname If a file name is provided in a constructor or open it is maintained as class variable nm and is accessible via name If no name is provided then nm remains null except that Files bound to the default files stdin stdout and stderr are automatically given the names stdin stdout stderr respectively The function setname may be used to change the internal name of the File This does not change the name of the physical file bound to the File The member function close closes a file The File destructor closes a file if it is open except that stdin stdout and stderr are flushed but left open for the system to close on program exit 46 User s Guide to the GNU C Class Library since some systems may require this and on others it does not matter remove closes
55. cece een eens 35 10 Header files for interfacing C to C 37 11 Utility functions for built in types 39 12 Library dynamic allocation primitives 41 13 14 15 16 17 18 19 20 21 22 23 User s Guide to the GNU C Class Library The new input output classes 43 The old I O library 004 45 14 1 File based classes 2 0 0 ccc cc ccc ence nee n ene enenns 45 14 2 Basic 1Q rvrrorarav vr arr vr arver r verre rann errre 46 14 3 File Control rrverarvvrv erverver verre reservene 46 14 4 File Status rverurrvrr ccc cnn ence nen nent eens 46 The Obstack class 0 0 ccc cece een e eee 49 The AllocRing class 00 cess cence 53 The String class 0 ccc eee eee eee eee 55 17 1 Constructors 0 ccc cece ene nnn een eneees 55 17 2 Examples 0 0 c cece cece cee tenet ete e neces 57 17 3 Comparing Searching and Matching 0000 57 17 4 Substring extraction 0 0 eee cece ee ee een eee 59 17 5 Concatenation 0 0 00 ccc cc cence n etn e ne nneneenes 60 17 6 Other manipulations 00 00 00 cece eee ene 61 17 7 Reading Writing and Conversion 0 0 e cece eens 62 The Integer class 0 cee eee eee neces 63 The Rational Class 0 cece cece eee 67 The Complex class 0 0 ccc cence eee cnet 69 Fixed pre
56. cision numbers 000000 71 Classes for Bit manipulation 73 22 1 BitSet ccc cn vr vervene erre rn nr vener 73 22 2 BitString roraravvvv arva va rrer vr erre ananas eneren 76 Random Number Generators and related classes Lee eee cece eee enn verre aa av 79 23 1 RNG ccc eee eee een b nee b eben enennenees 79 23 2 ACG erverv vr vr rv rr ra vvee 80 23 3 MLOG 2 nenene rererere rererere 80 23 4 Random cc ccc ccc cece eee raven 81 23 6 Erlang cee tener nnn n nett ene ee 81 23 7 Geometric 0 ee cee cen tenet ete n eens 81 23 8 HyperGeometric 0 0 0 ce cette ene e eee 82 23 9 NegativeExpntl 0 0 eee ene etn enees 82 23 10 Normal 0 c cee eee erreren rrer 82 23 11 LogNormal ec eter e enn e nnn nees 82 23 12 POISSON 0 Le eee eee ree eee een renee nen eres 82 23 13 DiscreteUniform 0 0 00 cece cee eee ee aes 83 23 14 Uniform 2 cc eee cent teen eens 83 23 15 Weibull 2 0 0 0 cee rererere reer 83 23 16 Randomlnteger 0 ieee cee tere re nnn nnes 83 24 Data Collection 0 c eee cece 85 24 1 SampleStatistic 0 0 0 cece tent eens 85 24 2 SampleHistogram 0 cece cee eee ee enn eee 86 25 Curses based classes cece eee e eee 87 26 List classes 0 cece eee eect ene eens 89 26 1 Constructors and assignment 0 00 c cere eee ee eens 89 26 2 List status 0 ke ce ec
57. company the work with a written offer valid for at least three years to give the same user the materials specified in Subsection 6a above for a charge no more than the cost of performing this distribution c If distribution of the work is made by offering access to copy from a designated place offer equivalent access to copy the above specified materials from the same place d Verify that the user has already received a copy of these materials or that you have already sent this user a copy For an executable the required form of the work that uses the Library must include any data and utility programs needed for reproducing the executable from it However as a special exception the source code distributed need not include anything that is normally distributed in either source or binary form with the major components compiler kernel and so on of the operating system on which the executable runs unless that component itself accompanies the executable It may happen that this requirement contradicts the license restrictions of other proprietary libraries that do not normally accompany the operating system Such a contradiction means you cannot use both them and the Library together in an executable that you distribute You may place library facilities that are a work based on the Library side by side in a single library together with other library facilities not covered by this License and distribute such a combined l
58. cond zero for equal and positive for greater Chapter 12 Library dynamic allocation primitives 41 12 Library dynamic allocation primitives Libg contains versions of malloc free realloc that were designed to be well tuned to C applications The source file malloc c contains some design and implementation details Here are the major user visible differences from most system malloc routines 1 These routines overwrite storage of freed space This means that it is never permissible to use a delete d object in any way Doing so will either result in trapped fatal errors or random aborts within malloc free or realloc 2 The routines tend to perform well when a large number of objects of the same size are allocated and freed You may find that it is not worth it to create your own special allocation schemes in such cases 3 The library sets top level operator new to call malloc and operator delete to call free Of course you may override these definitions in C programs by creating your own operators that will take precedence over the library versions However if you do so be sure to define both operator new and operator delete 4 These routines do not support the odd convention maintained by some versions of malloc that you may call realloc with a pointer that has been free d 5 The routines automatically perform simple checks on free d pointers that can often determine whether users have accidentally wr
59. d from opened for reading and not in a fail state or writable which returns true if the File can be written to File operations return their status via two means failure and success are represented via the logical state Also the return values of invoked stdio and system functions that return useful Chapter 14 The old I O library 47 numeric values not just failure success flags are held in a class variable accessible via iocount This is useful for example in determining the number of items actually read by the read function Like the AT amp T i o stream classes but unlike the description in the Stroustrup book p238 rdstate returns the bitwise OR of _eof fail and bad not necessarily distinct values The functions eof 9 fail bad and good can be used to test for each of these conditions independently _fail becomes set for any input operation that could not read in the desired data and for other failed operations As with all Unix IO _eof becomes true only when an input operations fails because of an end of file Therefore _eof is not immediately true after the last successful read of a file but only after one final read attempt Thus for input operations fail and _eof almost always become true at the same time bad is set for unbound files and may also be set by applications in order to communicate input corruption Conversely good is defined as 0 and is returned by rdstate if all is well The st
60. d of the plex However if the chunksize arguments to constructors are negative they leave space at the beginning All versions of Plexes support the following basic capabilities letting Plex stand for the type name constructed via the genclass utility e g intPlex doublePlex Assume declarations of Plex p q int i j base element x and Pix pix Plex p Declares p to be an initially zero sized Plex with low index of zero and the default chunk size For FPlexes chunk sizes represent maximum sizes Plex p int size Declares p to be an initially zero sized Plex with low index of zero and the indicated chunk size If size is negative then the Plex is created with free space at the beginning of the Plex allowing more efficient add_low operations Otherwise it leaves space at the end Plex p int low int size Declares p to be an initially zero sized Plex with low index of low and the indicated chunk size Chapter 29 Plex classes 103 Plex p int low int high Base initval int size 0 Declares p to be a Plex with indices from low to high initially filled with initval and the indicated chunk size if specified else the default or high low 1 whichever is greater Plex q p Declares q to be a copy of p P q Copies Plex q into p deleting its previous contents p length Returns the number of elements in the Plex p empty Returns true if Plex p contains no elements p full Returns true if Pl
61. de pseudo generic stan dard array based vector operations The corresponding header files are g include Vec hP and g include AVec hP Class Vec provides operations suitable for any base class that includes an equality operator Subclass AVec provides additional arithmetic operations suitable for base classes that include the full complement of arithmetic operators Vecs are constructed and assigned by copying Thus they should normally be passed by refer ence in applications programs Several mapping functions are provided that allow programmers to specify operations on vectors as a whole For illustrative purposes assume that classes intVec and intAVec have been generated via genclass 28 1 Constructors and assignment intVec a declares a to be an empty vector Its size may be changed via resize intVec a 10 declares a to be an uninitialized vector of ten elements numbered 0 9 intVec b 6 0 declares b to be a vector of six elements all initialized to zero Any value can be used as the initial fill argument a b Copies b to a a is resized to be the same as b a b at 2 4 constructs a from the 4 elements of b starting at b 2 Assume declarations of intVec a b cand int i x in the following 28 2 Status and access 98 User s Guide to the GNU C Class Library a capacity returns the number of elements that can be held in a a resize 20 sets a s length to 20 All elements are unchanged
62. do so and all its terms and conditions for copying distributing or modifying the Library or works based on it Each time you redistribute the Library or any work based on the Library the recipient automatically receives a license from the original licensor to copy distribute link with or modify the Library subject to these terms and conditions You may not impose any further restrictions on the recipients exercise of the rights granted herein You are not responsible for enforcing compliance by third parties to this License If as a consequence of a court judgment or allegation of patent infringement or for any other reason not limited to patent issues conditions are imposed on you whether by court order agreement or otherwise that contradict the conditions of this License they do not excuse you from the conditions of this License If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations then as a consequence you may not distribute the Library at all For example if a patent license would not permit royalty free redistribution of the Library by all those who receive copies directly or indirectly through you then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Library If any portion of this section is held invalid or unenforceable under any particular circumstance the balance of the section is inte
63. e roots These requirements apply to the modified work as a whole If identifiable sections of that work are not derived from the Library and can be reasonably considered independent and separate works in themselves then this License and its terms do not apply to those sections when you distribute them as separate works But when you distribute the same sections as part of a whole which is a work based on the Library the distribution of the whole must be on the terms of this License whose permissions for other licensees extend to the entire whole and thus to each and every part regardless of who wrote it Thus it is not the intent of this section to claim rights or contest your rights to work written entirely by you rather the intent is to exercise the right to control the distribution of derivative or collective works based on the Library In addition mere aggregation of another work not based on the Library with the Library or with a work based on the Library on a volume of a storage or distribution medium does not bring the other work under the scope of this License You may opt to apply the terms of the ordinary GNU General Public License instead of this License to a given copy of the Library To do this you must alter all the notices that refer to this License so that they refer to the ordinary GNU General Public License version 2 instead of to this License If a newer version than version 2 of the ordinary GNU General
64. e destroyed they invoke X X Any objects used in containers must have well behaved constructors and destructors If you want to create containers that merely reference point to objects that reside elsewhere and are not copied or destroyed inside the container you must use containers of pointers not containers of objects All prototypes are designed to generate HOMOGENOUS container classes There is no univer sally applicable method in C to support heterogenous object collections with elements of various subclasses of some specified base class The only way to get heterogenous structures is to use collec tions of pointers to objects not collections of objects which also requires you to take responsibility for managing storage for the objects pointed to yourself For example the following usage illustrates a commonly encountered danger in trying to use container classes for heterogenous structures class Base int x class Derived public Base int y BaseVHSet s class BaseVHSet generated via something like genclass Base ref VHSet void f Base b s add b OK Derived d s add d CHOP 26 User s Guide to the GNU C Class Library At the line flagged with CHOP a Base Base Base amp is called inside Set add Base amp not Derived Derived Derived amp Actually in VHSet a Base operator Base amp is used instead to place the element in an array s
65. ely entails formatting maintenance of various conventions etc Contributors are always given authorship credit and shown the final version for approval e Contributors must assign their copyright to FSF via a form sent out upon acceptance Assign ing copyright to FSF ensures that the code may be freely distributed e Assistance in providing documentation test files and debugging support is strongly encour aged Extensions comments and suggested modifications of existing libg features are also very welcome Table of Contents GNU LIBRARY GENERAL PUBLIC LICENSE 1 Preamble nnana nn ccc cc ene cn teen eee ne tne ene nn tn era 1 TERMS AND CONDITIONS FOR COPYING DISTRIBUTION AND MODIFICATION 0 0 0 0 era ccc ccc cn eee nn tne e ne nnenes 3 How to Apply These Terms to Your New Libraries 10 Contributors to GNU C library 11 1 Installing GNU C library 13 2 Trouble in Installation 0 cece eee 15 en en nee nn nee nee n eee e nbn btn e ete nb tenes 17 4 GNU C library stylistic conventions 19 5 Support for representation invariants 21 6 Introduction to container class prototypes 23 6 1 Example 20 ccc cece cece cece riro ence eee rrr rrr erreren 26 7 Variable Sized Object Representation 31 8 Some guidelines for using expression oriented classes 9 Pseudo indexes 0 ccc
66. ented with improper lists Also the reference counting storage management facility may fail to reclaim unused circularly linked nodes Several Lisp like higher order functions are supported e g map Typedef declarations for the required functional forms are provided int the h file For purposes of illustration assume the specification of class intList Common Lisp versions of supported operations are shown in brackets for comparison purposes 26 1 Constructors and assignment intList a setq anil Declares a to be a nil intList intList b 2 setq b cons 2 nil Declares b to be an intList with a head value of 2 and a nil tail intList c 3 b setq c cons 3 b Declares c to be an intList with a head value of 3 and b as its tail 90 User s Guide to the GNU C Class Library b a setq ba Sets b to be the same list as a Assume the declarations of intLists a b and c in the following See Chapter 9 Pix page 35 26 2 List status a null OR a null a returns true if a is null a valid listp a returns true if a is non null Inside a conditional test the void coercion may also be used as in if a intList nil intList may be used to null terminate a list as in intList f int x if x 0 return intList a length length a returns the length of a a list_length list length a returns the length of a or 1 if a is circul
67. er version with no visible difference Additionally all g specific constructs are conditionally compiled The library is designed to be compatible with any 2 0 C compiler libg has also contained workarounds for some limitations in g both g and libg are still undergoing rapid development and testing a task that is helped tremendously by the feedback of active users This manual is also still under development it has some catching up to do to include all the facilities now in the library libg is not the only freely available source of C class libraries Some notable alternative sources are Interviews and NIHCL InterViews has been available on the X windows X11 tapes and also from interviews stanford edu NIHCL is available by anonymous ftp from GNU archives such as the pub directory of prep ai mit edu although it is not supported by the FSF and needs some work before it will work with g As every C programmer knows the design moreso than the implementation of a C class library is something of a challenge Part of the reason is that C supports two partially incom patible styles of object oriented programming The forest approach involving a collection of free standing classes that can be mixed and matched versus the completely hierarchical smalltalk style approach in which all classes are derived from a common ancestor Of course both styles have advantages and disadvantages So far libg has adopted
68. es are formatted so that it is easy to quickly check them to determine function names parameters and so on Because of the different kinds of things that may appear in class declarations there is no perfect way to do this Any suggestions on developing a common class declaration formatting style are welcome e All classes use the same simple error exception handling strategy Almost every class has a member function named error char msg that invokes an associated error handler function via a pointer to that function so that the error handling function may be reset by program mers By default nearly all call lib_error_handler which prints the message and then aborts execution This system is subject to change In general errors are assumed to be non recoverable Library classes do not include code that allows graceful continuation after exceptions 20 User s Guide to the GNU C Class Library Chapter 5 Support for representation invariants 21 5 Support for representation invariants Most GNU C library classes possess a method named OK that is useful in helping to verify correct performance of class operations The OK operations checks the representation invariant of a class object This is a test to check whether the object is in a valid state In effect it is a sometimes partial verification of the library s promise that 1 class operations always leave objects in valid states and 2 the class protect
69. ese may be reversed The remaining members allow you to inspect and change low and high 23 15 Weibull The Weibull class implements a weibull distribution with parameters alpha and beta The first parameter to the class constructor is alpha and the second parameter is beta The remaining members allow you to inspect and change alpha and beta 23 16 RandomInteger The RandomInteger class is not a subclass of Random but a stand alone integer oriented class that is dependent on the RNG classes RandomInteger returns random integers uniformly from the closed interval low high The first parameter to the constructor is low and the second is high although both are optional The last argument is always a generator Additional members allow you to inspect and change low and high Random integers are generated using asInt or asLong Operator syntax is also available as a shorthand for asLong Because RandomInteger is often used in simulations for which uniform random integers are desired over a variety of ranges asLong and asInt have high as an optional argument Using this optional argument produces a single value from the new range but does not change the default range 84 User s Guide to the GNU C Class Library Chapter 24 Data Collection 85 24 Data Collection Libg currently provides two classes for data collection and analysis of the collected data 24 1 SampleStatistic Class SampleStatistic provides a means
70. ex p cannot be expanded This always returns false for XPlexes and MPlexes plil Returns a reference to the i th element of p An exception error occurs if i is not a valid index p valid i Returns true if i is a valid index into Plex p p low p high Return the minimum maximum valid index of the Plex or the high low fence if the plex is empty p ecnef p fence Return the index one position past the minimum maximum valid index p next i i p prev i Set i to the next previous index This index may not be within bounds p pix returns a reference to the item at Pix pix pix p firstQ pix p lastQ Return the minimum maximum valid Pix of the Plex or 0 if the plex is empty p next pix p prev pix set pix to the next previous Pix or 0 if there is none p owns pix Returns true if the Plex contains the element associated with pix p Pix to index pix If pix is a valid Pix to an element of the Plex returns its corresponding index else raises an exception 104 User s Guide to the GNU C Class Library ptr p index to Pix i if i is a valid index returns a the corresponding Pix p low_element p high element Return a reference to the element at the minimum maximum valid index An excep tion occurs if the Plex is empty p can add low p can add high Returns true if the plex can be extended one element downward upward These always return true for XPlex and M
71. finding via seek contains d deleting elements and c comparing via lt and m merging via amp sets XPSets implement unordered sets via XPlexes a O n O n d O n ce O n 2 m O n 2 OXPSets implement ordered sets via XPlexes a O n f O log n d O n e O n m O n SLSets implement unordered sets via linked lists a O n f O n d O n e O n 2 m O n 2 OSLSets implement ordered sets via linked lists a O n f O n d O n e O n m O n AVLSets implement ordered sets via threaded AVL trees a O log n f O log n d O log n lc O n m O n BSTSets implement ordered sets via binary search trees The trees may be manually rebalanced via the O n balance member function a O log n O n f O log n O n d O log n O n e O n m O n SplaySets implement ordered sets via Sleator and Tarjan s JACM 1985 splay trees The al gorithms use a version of simple top down splaying described on page 669 of the article Amortized a O log n f O log n d O log n c O n m O n log n VHSets implement unordered sets via hash tables The tables are automatically resized when their capacity is exhausted a O 1 O n f O 1 O n d O 1 O n e O n O n 2 m O m O n72 VOHSets implement unordered sets via ordered hash tables The tables are automatically resized when their capacity is ex
72. g sed All occurrences of the pseudo types lt T gt and lt C gt if there are two types are replaced with the indicated type and occur rences of lt T amp gt and lt C amp gt are replaced by just the types if val is specified or types followed by amp if ref is specified Programmers will frequently need to edit the h file in order to insert additional include directives or other modifications A simple utility prepend header to prepend other h files to generated files is provided in the distribution One dubious virtue of the prototyping mechanism is that because sources files not archived library classes are generated it is relatively simple for programmers to modify container classes in the common case where slight variations of standard container classes are required It is often a good idea for programmers to archive via ar generated classes into a files so that only those class functions actually used in a given application will be loaded The test subdirectory of the distribution shows an example of this Because of pragma interface directives the cc files should be compiled with 0 or DUSE_ LIBGXX_INLINES enabled Many container classes require specifications over and above the base class type For example classes that maintain some kind of ordering of elements require specification of a comparison func tion upon which to base the ordering This is accomplished via a prototy
73. h gt include lt GetOpt h gt Il int debug_flag compile_flag size_in_bytes int main int argc char argv Invokes ctor GetOpt int argc char argv char optstring GetOpt getopt argc argv dcs int option_char Invokes member function int operator void while Coption_char getopt EOF switch option_char case d debug_flag 1 break case c compile flag 1 break case s size in bytes atoi getopt optarg break case fprintf stderr usage 4s dcs lt size gt n argv 0 Unlike the C library version the libg GetOpt class uses its constructor to initialize class data members containing the argument count argument vector and the option string This simplifies the interface for each subsequent call to member function int operator void The C version on the other hand uses hidden static variables to retain the option string and argument list values between calls to getopt This complicates the getopt interface since the argument count argument vector and option string must be passed as parameters for each invocation For the C version the loop in the previous example becomes while option_char getopt argc argv dcs EOF 124 User s Guide to the GNU C Class Library which requires extra overhead to pass the parameters for every call Along with the GetOpt constructor and int operator void
74. hausted a O 1 O n f O 1 O n d O 1 O n e O n O n 2 m O m O n72 CHSets implement unordered sets via chained hash tables fa O 1 O n O 1 O n d O 1 O n e O n O n72 m O n O n72 116 User s Guide to the GNU C Class Library The different implementations differ in whether their constructors require an argument specifying their initial capacity Initial capacities are required for plex and hash table based Sets If none is given DEFAULT INITIAL CAPACITY from lt T gt defs h is used Sets support the following operations for some class Set instances a and b Pix ind and base element x Since all implementations are virtual derived classes of the lt T gt Set class it is possible to mix and match operations across different implementations although as usual operations are generally faster when the particular classes are specified in functions operating on Sets Pix based operations are more fully described in the section on Pixes See Chapter 9 Pix page 35 Set a or Set a int initial size Declares a to be an empty Set The second version is allowed in set classes that require initial capacity or sizing specifications a empty returns true if a is empty a length returns the number of elements in a Pix ind a add x inserts x into a returning its index a del x deletes x from a a clear deletes all elements from a a contains x returns true if x
75. he first occurrence of sublist b a contains int x member x a returns true if a contains x a contains b member b a returns true if a contains sublist b a position int x position x a returns the zero based index of x in a or 1 if x does not occur Chapter 26 List classes 93 int x a reduce f int base reduce f a initial value base Accumulates the result of applying int function f int int to successive elements of a starting with base 94 User s Guide to the GNU C Class Library Chapter 27 Linked Lists 95 27 Linked Lists SLLists provide pseudo generic singly linked lists DLLists provide doubly linked lists The lists are designed for the simple maintenance of elements in a linked structure and do not provide the more extensive operations or node sharing of class List They behave similarly to the slist and similar classes described by Stroustrup All list nodes are created dynamically Assignment is performed via copying Class DLList supports all SLList operations plus additional operations described below For purposes of illustration assume the specification of class intSLList In addition to the operations listed here SLLists support traversal via Pixes See Chapter 9 Pix page 35 intSLList a Declares a to be an empty list intSLList b a Sets b to an element by element copy of a v empty returns true if a contains no elements a length returns the
76. her a search or match depending on whether an index argument is provided x index lo returns the zero based index of the leftmost occurrence of substring lo 3 in this case The argument may be a String SubString char char or Regex x index 1 2 returns the index of the first of the leftmost occurrence of 1 found starting the search at position x 2 or 2 in this case x index 1 1 returns the index of the rightmost occurrence of I or 3 here x index 1 3 returns the index of the rightmost occurrence of 1 found by starting the search at the 3rd to the last position of x returning 2 in this case pos r search leo 3 len 0 returns the index of r in the char string of length 3 starting at position 0 also placing the length of the match in reference parameter len x contains He returns nonzero if the String x contains the substring He The argument may be a String SubString char char or Regex x contains el 1 returns nonzero if x contains the substring el at position 1 As in this example the second argument to contains if present means to match the substring only at that position and not to search elsewhere in the string x contains RXwhite returns nonzero if x contains any whitespace space tab or newline Recall that RXwhite is a global whitespace Regex x matches lo 3 returns nonzero if x starting at position 3 exactly matches lo with no trailing char
77. ial Generator In particular it is an implementation of the double MLCG described in Efficient and Portable Combined Random Number Generators by Pierre L Ecuyer appearing in Communications of the ACM Vol 31 No 6 This generator has a fairly long period and has been statistically analyzed to show that it gives good inter sample independence The MLCG MLCG constructor has two parameters both of which are seeds for the generator As in the MLCG generator both seeds are modified to give a better distribution of seed digits Thus Chapter 23 Random Number Generators and related classes 81 you can safely use values such as 0 or 1 for the seeds The MLCG generator used much less state than the ACG generator only two longwords 8 bytes are needed for each generator 23 4 Random A random number generator may be declared by first declaring a RNG and then a Random For example ACG gen 10 20 NegativeExpntl rnd 1 0 amp gen declares an additive congruential generator with seed 10 and table size 20 that is used to generate exponentially distributed values with mean of 1 0 The virtual member Random operator is the common way of extracting a random number from a particular distribution The base class Random does not implement operator This is performed by each of the subclasses Thus given the above declaration of rnd new random values may be obtained via for example double next_exp_rand rnd C
78. ibe a e A revision of the File based classes that will use the GNU stdio library and also be 100 compatible even at the streambuf level with the AT amp T 2 0 stream classes e Additional container class prototypes e generic Matrix class prototypes e A task package probably based on Dirk Grunwald s threads package 38 2 Wish List Some things that people have mentioned that they would like to see in libg but for which there have not been any offers e A method to automatically convert or incorporate libg classes so they can be used directly in Gorlen s OOPS environment e class browser e A better general exception handling strategy e Better documentation 38 3 How to contribute Programmers who have written C classes that they believe to be of general interest are encourage to write to dl at rocky oswego edu Contributing code is not difficult Here are some general guidelines e FSF must maintain the right to accept or reject potential contributions Generally the only reasons for rejecting contributions are cases where they duplicate existing or nearly released 126 User s Guide to the GNU C Class Library code contain unremovable specific machine dependencies or are somehow incompatible with the rest of the library e Acceptance of contributions means that the code is accepted for adaptation into libg FSF must reserve the right to make various editorial changes in code Very often this mer
79. ibrary provided that the separate distribution of the work based on the Library and of the other library facilities is otherwise permitted and provided that you do these two things a Accompany the combined library with a copy of the same work based on the Library uncombined with any other library facilities This must be distributed under the terms of the Sections above b Give prominent notice with the combined library of the fact that part of it is a work based GNU LIBRARY GENERAL PUBLIC LICENSE 7 10 11 on the Library and explaining where to find the accompanying uncombined form of the same work You may not copy modify sublicense link with or distribute the Library except as expressly provided under this License Any attempt otherwise to copy modify sublicense link with or distribute the Library is void and will automatically terminate your rights under this License However parties who have received copies or rights from you under this License will not have their licenses terminated so long as such parties remain in full compliance You are not required to accept this License since you have not signed it However nothing else grants you permission to modify or distribute the Library or its derivative works These actions are prohibited by law if you do not accept this License Therefore by modifying or distributing the Library or any work based on the Library you indicate your acceptance of this License to
80. icense the GNU Library General Public License applies to certain designated libraries This license is quite different from the ordinary one be sure to read it in full and don t assume that anything in it is the same as in the ordinary license The reason we have a separate public license for some libraries is that they blur the distinction we usually make between modifying or adding to a program and simply using it Linking a program with a library without changing the library is in some sense simply using the library and is analogous to running a utility program or application program However in a textual and legal sense the linked executable is a combined work a derivative of the original library and the ordinary General Public License treats it as such Because of this blurred distinction using the ordinary General Public License for libraries did not effectively promote software sharing because most developers did not use the libraries We concluded that weaker conditions might promote sharing better However unrestricted linking of non free programs would deprive the users of those programs of all benefit from the free status of the libraries themselves This Library General Public License is intended to permit developers of non free programs to use free libraries while preserving your freedom as a user of such programs to change the free libraries that are incorporated in them We have not seen how to achieve this as regard
81. ime e You can run one obstack per control block e You may have as many control blocks as you dare e Because of the way we do it you can unwind a obstack back to a previous state You may remove objects much as you would with a stack The obstack data structure is used in many places in the GNU C compiler Differences from the the GNU C version 1 The obvious differences stemming from the use of classes and inline functions instead of structs and macros The C init and begin macros are replaced by constructors 2 Overloaded function names are used for grow and others rather than the C grow grow0 etc 3 All dynamic allocation uses the the built in new operator This restricts flexibility by a little but maintains compatibility with usual C conventions 4 There are now two versions of finish 1 finish behaves like the C version 2 finish char terminator adds terminator and then calls finish This enables the normal invocation of finish 0 to wrap up a string being grown character by character 5 There are special versions of grow const char s and copy const char s that add the null terminated string s after computing its length 6 The shrink and contains functions are provided 52 User s Guide to the GNU C Class Library Chapter 16 The AllocRing class 53 16 The AllocRing class An AllocRing is a bounded ring circular list each of whose elements contains a pointer to some sp
82. in file Person SSN Map h and Person SSN Map cc To create the AVL implementation type genclass 2 Person ref SSN val AVLMap This creates the class PersonSSNAVLMap in Person SSN AVLMap h and Person SSN AVLMap cc To use the AVL implementation compile the two generated cc files and specify include Person SSN AVLMap h in the application program All other files are included in the right ways automatically One last consideration peculiar to Maps is to pick a reasonable default contents when declaring an AVLMap Zero might be appropriate here so you might declare a Map PersonSSNAVLMap m SSN 0 Chapter 6 Introduction to container class prototypes 29 Suppose you wanted a VHMap instead of an AVLMap Besides generating different implementations there are two differences in how you should prepare the defs file First because a VHMap uses a C array internally and because C array slots are initialized differently than single elements you must ensure that class Person contains 1 a no argument constructor and 2 an assignment operator You could arrange this via class Person Person void operator const Person amp p nm p nm addr p addr The lack of action in the constructor is OK here because Strings possess usable no argument constructors You also need to edit Person defs h to indicate a usable hash function and default capacity
83. is at least twice as long as a short This assumption hides beneath almost all primitive operations and would be very difficult to change It also relies on correct behavior of unsigned arithmetic operations Some of the arithmetic algorithms are very loosely based on those provided in the MIT Scheme bignum c release which is Copyright c 1987 Massachusetts Institute of Technology Their use here falls within the provisions described in the Scheme release Integers may be constructed in the following ways Integer x Declares an uninitialized Integer Integer x 2 Integer y 2 Set x and y to the Integer value 2 Integer u x Integer v x Set u and v to the same value as x long Integer as_long const Method Used to coerce an Integer back into longs via the long coercion operator If the Integer cannot fit into a long this returns MINLONG or MAXLONG depending on the sign where MINLONG is the most negative and MAXLONG is the most positive representable long int Integer fitsin_long const Method Returns true iff the Integer is lt MAXLONG and gt MINLONG double Integer as_double const Method Coerce the Integer to a double with potential loss of precision HUGE is returned if the Integer cannot fit into a double 64 User s Guide to the GNU C Class Library int Integer fitsin_double const Method Returns true iff the Integer can fit into a double All of the usual arithmetic operators are pr
84. itten beyond the boundaries of allocated space resulting in a fatal error 6 The function malloc_usable_size void p returns the number of bytes actually allocated for p For a valid pointer i e one that has been malloc d or realloc d but not yet free d this will return a number greater than or equal to the requested size else it will normally return 0 Unfortunately a non zero return can not be an absolutely perfect indication of lack of error If a chunk has been free d but then re allocated for a different purpose somewhere elsewhere then malloc_usable_size will return non zero Despite this the function can be very valuable for performing run time consistency checks 7 malloc requires 8 bytes of overhead per allocated chunk plus a mmaximum alignment adjust ment of 8 bytes The number of bytes of usable space is exactly as requested rounded to the nearest 8 byte boundary 8 The routines do not contain any synchronization support for multiprocessing If you perform global allocation on a shared memory multiprocessor you should disable compilation and use of libg malloc in the distribution Makefile and use your system version of malloc 42 User s Guide to the GNU C Class Library Chapter 13 The new input output classes 43 13 The new input output classes The iostream classes implement most of the features of AT amp T version 2 0 iostream library classes and most of the features of the ANSI X3J16 lib
85. listic conventions e C source files have file extension cc Both C compatibility header files and class declara tion files have extension h e C class names begin with capital letters except for istream and ostream for AT amp T C compatibility Multi word class names capitalize each word with no underscore separation e Include files that define C classes begin with capital letters as do the names of the classes themselves stream h is uncapitalized for AT amp T C compatibility e Include files that supply function prototypes for other C functions system calls and libraries are all lower case e All include files define a preprocessor variable _X_h where X is the name of the file and conditionally compile only if this has not been already defined The pragma once facility is also used to avoid re inclusion e Structures and objects that must be publicly defined but are not intended for public use have names beginning with an underscore for example the _Srep struct which is used only by the String and SubString classes e The underscore is used to separate components of long function names e g set_File_exception_handler e When a function could be usefully defined either as a member or a friend it is generally a member if it modifies and or returns itself else it is a friend There are cases where naturalness of expression wins out over this rule e Class declaration fil
86. lot but with the same effect So only the Base part is copied as a VHSet element a so called chopped copy In this case it has an x part but no y part and a Base not Derived vtable Objects formed via chopped copies are rarely sensible To avoid this you must resort to pointers typedef Base BasePtr BasePtrVHSet s class BaseVHSet generated via something like genclass BasePtr val VHSet void 0 Base bp new Base s add b Base dp new Derived s add d works fine Don t forget to delete bp and dp sometime The VHSet won t do this for you 6 1 Example The prototypes can be difficult to use on first attempt Here is an example that may be helpful The utilities in the proto kit simplify much of the actions described but are not used here Suppose you create a class Person and want to make an Map that links the social security numbers associated with each person You start off with a file Person h include lt String h gt class Person String nm String addr Il public Chapter 6 Introduction to container class prototypes 27 const String amp name return nm const String amp address return addr void print And in file SSN h typedef unsigned int SSN Your first decision is what storage usage strategy to use There are several reasonable alterna tives here You might create an object collection of Person
87. ls outside the scope of this License However linking a work that uses the Library with the Library creates an executable that is a derivative of the Library because it contains portions of the Library rather than a work that uses the library The executable is therefore covered by this License Section 6 states terms for distribution of such executables When a work that uses the Library uses material from a header file that is part of the Library the object code for the work may be a derivative work of the Library even though the source code is not Whether this is true is especially significant if the work can be linked without the Library or if the work is itself a library The threshold for this to be true is not precisely defined by law If such an object file uses only numerical parameters data structure layouts and accessors and small macros and small inline functions ten lines or less in length then the use of the object file is unrestricted regardless of whether it is legally a derivative work Executables containing this object code plus portions of the Library will still fall under Section 6 Otherwise if the work is a derivative of the Library you may distribute the object code for the work under the terms of Section 6 Any executables containing that work also fall under Section 6 whether or not they are linked directly with the Library itself 6 As an exception to the Sections above you may al
88. lue BUFSIZ and the declaration of _iobuf should be checked before using C versions of assert macros generic h new h String concatenation macros useful in creating generic classes They are similar in function to the AT amp T CC versions Declarations of the default global operator new the two argument placement version and associated error handlers 38 User s Guide to the GNU C Class Library Chapter 11 Utility functions for built in types 39 11 Utility functions for built in types Files builtin h and corresponding cc implementation files contain various convenient inline and non inline utility functions These include useful enumeration types such as TRUE FALSE the type definition for pointers to libg error handling functions and the following functions long abs long x double abs double x inline versions of abs Note that the standard libc a version int abs int is not declared as inline void clearbit long amp x long b clears the b th bit of x inline void setbit long amp x long b sets the b th bit of x inline int testbit long x long b returns the b th bit of x inline int even long y returns true if x is even inline int odd long y returns true is x is odd inline int sign long x int sign double x returns 1 0 or 1 indicating whether x is less than equal to or greater than zero inline long gcd long x long y retu
89. mples in bucket i int b h buckets returns the number of buckets h printBuckets ostream s prints bucket counts on ostream s double bound h bucketThreshold int i returns the upper bound of bucket i Chapter 25 Curses based classes 87 25 Curses based classes The CursesWindow class is a repackaging of standard curses library features into a class It relies on curses h The supplied curses h is a fairly conservative declaration of curses library features and does not include features like screen or X window support It is for the most part an adaptation rather than an improvement of C based curses h files The only substantive changes are the declarations of many functions as inline functions rather than macros which was done solely to allow overloading The CursesWindow class encapsulates curses window functions within a class Only those func tions that control windows are included Terminal control functions and macros like cbreak are not part of the class All CursesWindows member functions have names identical to the corresponding curses library functions except that the w prefix is generally dropped Descriptions of these functions may be found in your local curses library documentation A CursesWindow may be declared via CursesWindow w WINDOW win attaches w to the existing WINDOW win This is constructor is normally used only in the following special case CursesWindow w s
90. ms come to the top of the heap lasses support the following operations for some PQ class Heap instance h Pix ind and base class variable x h empty h length returns true if there are no elements in the PQ returns the number of elements in h ind h enq x x h deq h front Places x in the PQ and returns its index Dequeues the minimum element of the PQ into x or generates an error if the PQ is empty returns a reference to the minimum element h del_front deletes the minimum element 114 User s Guide to the GNU C Class Library h clear deletes all elements from h h contains x returns true if x is in h h ind returns a reference to the item indexed by ind ind h first returns the Pix of first item in the PQ or 0 if empty This need not be the Pix of the least element h next ind advances ind to the Pix of next element or 0 if there are no more ind h seek x Sets ind to the Pix of x or 0 if x is not in h h del ind deletes the item with Pix ind Chapter 34 Set class prototypes 115 34 Set class prototypes Set classes maintain unbounded collections of items containing no duplicate elements These are currently implemented in several ways differing in representation strategy algorithmic efficiency and appropriateness for various tasks Listed next to each are average followed by worst case if different time complexities for a adding f
91. n the BitString and all binary operations across unequal length BitStrings assume a virtual bit of zero The amp operation returns a BitString with a length equal to the minimum length of the operands and return one with length of the maximum Set based relational operations lt lt gt gt follow the same rules A string like lex icographic comparison function lcompare tests the lexicographic relation between two BitStrings Chapter 22 Classes for Bit manipulation 77 For example lcompare 1100 0101 returns 1 since the first BitString starts with 1 and the second with 0 Individual bit setting testing and iterator operations set clear invert test first next last prev are also like those for BitSets BitStrings are automatically expanded when setting bits at positions greater than their current length The string based capabilities are just as those for class String BitStrings may be concatenated searched index contains matches and extracted into BitSubStrings before at after which may be assigned and otherwise manipulated Other string based utility functions reverse common_prefix common_suffix are also provided These have the same capabilities and descriptions as those for Strings String oriented operations can also be performed with a mask via class BitPattern BitPatterns consist of two BitStrings a pattern and a mask On searching and matching bits in the pattern
92. nded to apply and the section as a whole is intended to apply in other circumstances It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims this section has the sole purpose of protecting the integrity of the free software distribution system which is implemented by public license practices Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system it is up to the author donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License 12 13 14 15 16 User s Guide to the GNU C Class Library If the distribution and or use of the Library is restricted in certain countries either by patents or by copyrighted interfaces the original copyright holder who places the Library under this License may add an explicit geographical distribution limitation excluding those countries so that distribution is permitted only in or among countries not thus excluded In such case this License incorporates the limitation as if written in the body of this License The Free Software Foundation may publish revised and or new versions of the Library General Public License
93. nt to and from Integer etc There are pro s and con s to circular converters since they can sometimes lead to the conversion from a builtin type through to a class function and back to a builtin type without any special attention on the part of the programmer both for better and worse 32 User s Guide to the GNU C Class Library Most of these classes also provide special case operators and functions mixing basic with class types as a way to avoid constructors in cases where the operations do not rely on anything special about the representations For example there is a special case concatenation operator for a String concatenated with a char since building the result does not rely on anything about the String header Again there are arguments both for and against this approach Supporting these cases adds a non trivial degree of mainly inline function proliferation but results in more efficient operations Efficiency wins out over parsimony here as part of the goal to produce classes that provide sufficient functionality and efficiency so that programmers are not tempted to try to manipulate or bypass the underlying representations Chapter 8 Some guidelines for using expression oriented classes 33 8 Some guidelines for using expression oriented classes The fact that C allows operators to be overloaded for user defined classes can make pro gramming with library classes like Integer String and so on very convenient Howeve
94. nters A Pix is a kind of key that is translated into an element access by the class In virtually all cases Pixes are pointers to some kind internal storage cells The containers use these pointers to extract items Pixes support traversal and inspection of elements in a collection using analogs of array index ing However they are pointer like in that 0 is treated as an invalid Pix and unsafe insofar as programmers can attempt to access nonexistent elements via dangling or otherwise invalid Pixes without first checking for their validity In general it is a very bad idea to perform traversals in the the midst of destructive modifications to containers Typical applications might include code using the idiom for Pix i a first i 0 a next i use a i for some container a and function use Classes supporting the use of Pixes always contain the following methods assuming a container a of element types of Base Pix i a first Set i to index the first element of a or 0 if a is empty a next i advance i to the next element of a or 0 if there is no next element Base x a i a i x a i returns a reference to the element indexed by i int present a owns i returns true if Pix i is a valid Pix in a This is often a relatively slow operation since the collection must usually traverse through elements to see if any correspond to the Pix 36 User s Guide to the GNU C Class Library Some container classes
95. number of elements in a v prepend x places x at the front of the list v append x places x at the end of the list a join b places all nodes from b to the end of a simultaneously destroying b P4 iT a front returns a reference to the item stored at the head of the list or triggers an error if the list is empty a rear returns a reference to the rear of the list or triggers an error if the list is empty x a remove front deletes and returns the item stored at the head of the list a del front deletes the first element without returning it 96 User s Guide to the GNU C Class Library a clear deletes all items from the list a ins after Pix i item inserts item after position i If i is null insertion is at the front a del after Pix i deletes the element following i Ifi is 0 the first item is deleted 27 1 Doubly linked lists Class DLList supports the following additional operations as well as backward traversal via Pixes x a remove_rear deletes and returns the item stored at the rear of the list a del_rear deletes the last element without returning it a ins_before Pix i x inserts x before the i a del Pix amp iint dir 1 deletes the item at the current position then advances forward if dir is positive else backward Chapter 28 Vector classes 97 28 Vector classes The files g include Vec ccP and g include AVec ccP provi
96. o the GNU C Class Library Plexes may be indexed and used like arrays although traversal syntax is slightly different Even though Plexes maintain elements in lists of chunks they are implemented so that iteration and other constructs that maintain locality of reference require very little overhead over that for simple array traversal Pix based traversal is also supported For example for a plex p of ints the following traversal methods could be used for int i p low i lt p fence p next i use p il for int i p high i gt p ecnef p prev i use p il for Pix t p first t 0 p next t use p i for Pix t p last t 0 p prev t use p i Except for MPlexes simply using i and i works just as well as p next i and p prev i when traversing by index Index based traversal is generally a bit faster than Pix based traversal XPlexes and MPlexes are less than optimal for applications in which widely scattered elements are indexed as might occur when using Plexes as hash tables or manually allocated linked lists In such applications RPlexes are often preferable RPlexes use a secondary chunk index table that requires slightly greater but entirely uniform overhead per index operation Even though they may grow in either direction Plexes are normally constructed so that their natural growth direction is upwards in that default chunk construction leaves free space if present at the en
97. of accumulating samples of double values and pro viding common sample statistics Assume declaration of double x SampleStatistic a declares and initializes a a reset re initializes a at x adds sample x int n a samples returns the number of samples x a mean returns the means of the samples x a var returns the sample variance of the samples x a stdDev returns the sample standard deviation of the samples x a min returns the minimum encountered sample x a max returns the maximum encountered sample x a confidence int p returns the p percent 0 lt p lt 100 confidence interval x a confidence double p returns the p probability 0 lt p lt 1 confidence interval 86 User s Guide to the GNU C Class Library 24 2 SampleHistogram Class SampleHistogram is a derived class of SampleStatistic that supports collection and display of samples in bucketed intervals It supports the following in addition to SampleStatisic operations SampleHistogram h double lo double hi double width declares and initializes h to have buckets of size width from lo to hi If the optional argument width is not specified 10 buckets are created The first bucket and also holds samples less than lo and the last one holds samples greater than hi int n h similarSamples x returns the number of samples in the same bucket as x int n h inBucket int i returns the number of sa
98. ominator relatively prime and with the denominator strictly positive Rational arithmetic and relational operators are provided lt lt gt gt Operations resulting in a rational number with zero denominator trigger an exception Rationals may be constructed and used in the following ways Rational x Declares an uninitialized Rational Rational x 2 Rational y 2 Set x and y to the Rational value 2 1 Rational x 2 3 Sets x to the Rational value 2 3 Rational x 1 2 Sets x to a Rational value close to 1 2 Any double precision value may be used to construct a Rational The Rational will possess exactly as much precision as the double Double values that do not have precise floating point equivalents like 1 2 produce similarly imprecise rational values Rational x Integer 123 Integer 4567 Sets x to the Rational value 123 4567 Rational u x Rational v x Set u and v to the same value as x double Rational x A Rational may be coerced to a double with potential loss of precision HUGE is returned if it will not fit Rational abs x returns the absolute value of x void x negate negates x void x invert sets x to 1 x int sign x returns 0 if x is zero 1 if positive and 1 if negative 68 Rational sqr x returns x x Rational pow x Integer y returns x to the y power Integer x numerator returns the numerator Integer x
99. ost effectively convey the exclusion of warranty and each file should have at least the copyright line and a pointer to where the full notice is found one line to give the library s name and an idea of what it does Copyright C year name of author This library is free software you can redistribute it and or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation either version 2 of the License or at your option any later version This library is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU Library General Public License for more details You should have received a copy of the GNU Library General Public License along with this library if not write to the Free Software Foundation Inc 59 Temple Place Suite 330 Cambridge MA 02139 USA Also add information on how to contact you by electronic and paper mail You should also get your employer if you work as a programmer or your school if any to sign a copyright disclaimer for the library if necessary Here is a sample alter the names Yoyodyne Inc hereby disclaims all copyright interest in the library Frob a library for tweaking knobs written by James Random Hacker signature of Ty Coon 1 April 1990 Ty Coon President of Vice That s all there is to it
100. otherwise noted void divide const Integer amp x const Integer amp y Integer amp q Function Integer amp r Sets q to the quotient and r to the remainder of x and y q and r are returned by reference Integer pow const Integer amp x const Integer amp p Function Returns x raised to the power p Integer Ipow long x long p Function Returns x raised to the power p Integer gcd const Integer amp x const Integer amp p Function Returns the greatest common divisor of x and y Chapter 18 The Integer class 65 Integer lem const Integer amp x const Integer amp p Function Returns the least common multiple of x and y Integer abs const Integer amp x Function Returns the absolute value of x void Integer negate Method Negates this in place Integer sqr x returns x x Integer sqrt x returns the floor of the square root of x long lg x returns the floor of the base 2 logarithm of abs x int sign x returns 1 if x is negative 0 if zero else 1 Using if sign x 0 is a generally faster method of testing for zero than using relational operators int even x returns true if x is an even number int odd x returns true if x is an odd number void setbit Integer amp x long b sets the b th bit counting right to left from zero of x to 1 void clearbit Integer amp x long b sets the b th bit of x to 0 int testbit Integer x long b returns true if the b th bit of x is 1
101. ovided h h lt lt gt gt All operators support special versions for mixed arguments of Integers and regular C longs in order to avoid useless coercions as well as to allow automatic promotion of shorts and ints to longs so that they may be applied without additional Integer coercion operators The only operators that behave differently than the corresponding int or long operators are and Because C does not distinguish prefix from postfix application these are declared as void operators so that no confusion can result from applying them as postfix Thus for Integers x and y x y x is correct but y x and y x are not Bitwise operators amp lt lt gt gt amp lt lt gt gt are also provided However these operate on sign magnitude rather than two s complement representations The sign of the result is arbitrarily taken as the sign of the first argument For example Integer 3 amp Integer 5 returns Integer 1 not 3 as it would using two s complement Also the complement operator complements only those bits needed for the representation Bit operators are also provided in the BitSet and BitString classes One of these classes should be used instead of Integers when the results of bit manipulations are not interpreted numerically The following utility functions are also provided All arguments are Integers unless
102. ow addresses When you want to build a symbol in the chunk you just add chars above the current high water mark in the chunk When you have finished adding chars because you got to the end of the symbol you know how long the chars are and you can create a new object Mostly the chars will not burst over the highest address of the chunk because you would typically expect a chunk to be say 100 times as long as an average object In case that isn t clear when we have enough chars to make up the object they are already contiguous in the chunk guaranteed so we just point to it where it lies No moving of chars is needed and this is the second win potentially long strings need never be explicitly shuffled Once an object is formed it does not change its address during its lifetime Chapter 15 The Obstack class 51 When the chars burst over a chunk boundary we allocate a larger chunk and then copy the partly formed object from the end of the old chunk to the beginning of the new larger chunk We then carry on accreting characters to the end of the object as we normally would A special version of grow is provided to add a single char at a time to a growing object Summary e We allocate large chunks e We carve out one object at a time from the current chunk e Once carved an object never moves e We are free to append data of any size to the currently growing object e Exactly one object is growing in an obstack at any one t
103. pe file defs hP that contains macros for these functions While these macros default to perform reasonable actions they can and should be changed in particular cases Most prototypes require only one or a few of these No harm is done if unused macros are defined to perform nonsensical actions The macros are DEFAULT_INITIAL_CAPACITY The initial capacity for containers e g hash tables that require an initial capacity argument for constructors Default 100 lt T gt EQ a b return true if a is considered equal to b for the purposes of locating etc an element in a container Default a b lt T gt LE a b return true if a is less than or equal to b Default a lt b Chapter 6 Introduction to container class prototypes 25 lt T gt CMP a b return an integer lt 0 if a lt b 0 if a b or gt 0 if a gt b Default a lt b a b 0 1 1 lt T gt HASH a return an unsigned integer representing the hash of a Default hash a where extern unsigned int hash lt T amp gt note several useful hash functions are declared in builtin h and defined in hash cc Nearly all prototypes container classes support container traversal via Pix pseudo indices as described elsewhere All object containers must perform either a X X X amp or X X followed by X operator X amp to copy objects into containers The latter form is used for containers built from C arrays like VHSets When containers ar
104. r it is worth becoming familiar with some of the inherent limitations and problems associated with such operators Many operators are constructive i e create a new object based on some function of some arguments Sometimes the creation of such objects is wasteful Most library classes supporting expressions contain facilities that help you avoid such waste For example for Integer a b c c a b a the plus operator is called to sum a and b creating a new temporary object as its result This temporary is then added with a creating another temporary which is finally copied into c and the temporaries are then deleted In other words this code might have an effect similar to Integer a b c Integer ti a t1 b Integer t2 t1 t2 a c t2 For small objects simple operators and or non time space critical programs creation of tem poraries is not a big problem However often when fine tuning a program it may be a good idea to rewrite such code in a less pleasant but more efficient manner For builtin types like ints and floats C and C compilers already know how to optimize such expressions to reduce the need for temporaries Unfortunately this is not true for C user defined types for the simple but very annoying in this context reason that nothing at all is guaranteed about the semantics of overloaded operators and their interrelations For example if the above expression just involved ints not Integers
105. rary draft which is based on the AT amp T design These classes are available in libg for convenience and for compatibility with older releases however since the iostream classes are licensed under less stringent terms than libg they are now also available in a separate library called libio and documented in a separate manual corresponding to that library See section Introduction in The GNU C Iostream Library 44 User s Guide to the GNU C Class Library Chapter 14 The old I O library 45 14 The old I O library WARNING This chapter describes classes that are obsolete These classes are normally not available when libg is installed normally The sources are currently included in the distribution and you can configure libg to use these classes instead of the new iostream classes This is only a temporary measure you should convert your code to use iostreams as soon as possible The iostream classes provide some compatibility support but it is very incomplete there is no longer a File class 14 1 File based classes The File class supports basic IO on Unix files Operations are based on common C stdio library functions File serves as the base class for istreams ostreams and other derived classes It contains the interface between the Unix stdio file library and these more structured classes Most operations are implemented as simple calls to stdio functions File class operations are also fully compati
106. rent time complexities for a accessing via op contains d deleting elements AVLMaps implement ordered Maps via threaded AVL trees a O log n d O log n RAVLMaps Similar but also maintain ranking information used via ranktoPix int r that re turns the Pix of the item at rank r and rank key that returns the rank of the corresponding item a O log n d O log n SplayMaps implement ordered Maps via Sleator and Tarjan s JACM 1985 splay trees The algorithms use a version of simple top down splaying described on page 669 of the article Amortized a O log n d O log n VHMaps implement unordered Maps via hash tables The tables are automatically resized when their capacity is exhausted fa O 1 O n d O 1 O a CHMaps implement unordered Maps via chained hash tables fa O 1 O n d O 1 O n The different implementations differ in whether their constructors require an argument specifying their initial capacity Initial capacities are required for hash table based Maps If none is given DEFAULT_INITIAL_CAPACITY from lt T gt defs h is used All Map classes share the following operations for some Map class Map instance d Pix ind and key variable k and contents variable x Pix based operations are more fully described in the section on Pixes See Chapter 9 Pix page 35 Map d x Map d x int initial_capacity Declare d to be an empty Map The required argument
107. ring Hello String x A String y A Set x and y to the string value A String u x String v x Set u and v to the same string as String x String u x at 1 4 String v x at 1 4 Set u and v to the length 4 substring of x starting at position 1 counting indexes from 0 String x abc 2 Sets x to ab i e the first 2 characters of abc 56 User s Guide to the GNU C Class Library String x dec 20 Sets x to 20 As here Strings may be initialized or assigned the results of any char function There are no directly accessible forms for declaring SubString variables The declaration Regex r a zA Z a zA Z0 9_ creates a compiled regular expression suitable for use in String operations described below In this case one that matches any C identifier The first argument may also be a String Be careful in distinguishing the role of backslashes in quoted GNU C char constants versus those in Regexes For example Regex that matches either one or more tabs or all strings beginning with ba and ending with any number of occurrences of na could be declared as Regex r VG t VDU AVIAN Coa na VUA M0 Note that only one backslash is needed to signify the tab but two are needed for the parenthesization and virgule since the GNU C lexical analyzer decodes and strips backslashes before they are seen by Regex There are three additional optional arguments to the Regex constructor that are le
108. rns the greatest common divisor of x and y long lcm long x long y returns the least common multiple of x and y long lg long x returns the floor of the base 2 log of x long pow long x long y double pow double x long y returns x to the integer power y using via the iterative O log y Russian peasant method long sqr long x double sqr double x returns x squared inline long sqrt long y returns the floor of the square root of x 40 User s Guide to the GNU C Class Library unsigned int hashpjw const char s a hash function for null terminated char strings using the method described in Aho Sethi amp Ullman p 436 unsigned int multiplicativehash int x a hash function for integers that returns the lower bits of multiplying x by the golden ratio times pow 2 32 See Knuth Vol 3 p 508 unsigned int foldhash double x a hash function for doubles that exclusive or s the first and second words of x returning the result as an integer double start_timer Starts a process timer double return elapsed time double last time Returns the process time since last time If last time 0 returns the time since the last start timer Returns 1 if start timer was not first called File Maxima h includes versions of MAX MIN for builtin types File compare h includes versions of compare x y for builtin types These return negative if the first argument is less than the se
109. rns true if queue q is empty q full returns true if queue q is full XPQueues and SLQueues are never full q length returns the current number of elements in the queue q enq x enqueues x on queue q x q deq dequeues and returns the front of queue q front returns a reference to the front of queue q del_front dequeues but does not return the front of queue q clear removes all elements from the queue 110 User s Guide to the GNU C Class Library Chapter 32 Double ended Queues 111 32 Double ended Queues Deques are declared as an abstract class They are currently implemented in two ways XPDeque implement dynamically sized Deques via XPlexes DLDeque implement dynamically size Deques via linked lists All possess the same capabilities They differ only in constructors XPDeque constructors optionally take a chunk size argument DLDeque constructors take no argument Double ended queues support both stack like and queue like capabilities Assume the declaration of a base element x Deque d or Deque d int initial capacity declares a deque d empty returns true if deque d is empty d full returns true if deque d is full Always returns false in current implementations d length returns the current number of elements in the deque d enq x inserts x at the rear of deque d d push x inserts x at the front of deque d x d deq dequeues and returns the front of deque d fron
110. s a pointer collection of pointers to Persons or even a simple String map housing either copies of pointers to the names of Persons since other fields are unused for purposes of the Map In an object collection instances of class Person live inside the Map while in a pointer collection the instances live elsewhere Also as above if instances of subclasses of Person are to be used inside the Map you must use pointers In a String Map the same difference holds but now only for the name fields Any of these choices might make sense in particular applications The second choice is the Map implementation strategy Either a tree or a hash table might make sense Suppose you want an AVL tree Map There are two things to now check First as an object collection the AVLMap requires that the elsement class contain an X X amp constructor In C if you don t specify such a constructor one is constructed for you but it is a very good idea to always do this yourself to avoid surprises In this example you d use something like class Person Person const Person amp p nm p nm addr p addr F Also an AVLMap requires a comparison function for elements in order to maintain order Rather than requiring you to write a particular comparison function a defs file is consulted to determine how to compare items You must create and edit such a file Before creating Person defs h you must first make one
111. s changes in header files but we have achieved it as regards changes in the actual functions of the Library The hope is that this will lead to faster development of free libraries GNU LIBRARY GENERAL PUBLIC LICENSE 3 The precise terms and conditions for copying distribution and modification follow Pay close attention to the difference between a work based on the library and a work that uses the library The former contains code derived from the library while the latter only works together with the library Note that it is possible for a library to be covered by the ordinary General Public License rather than by this special one TERMS AND CONDITIONS FOR COPYING DISTRIBUTION AND MODIFICATION 0 This License Agreement applies to any software library which contains a notice placed by the copyright holder or other authorized party saying it may be distributed under the terms of this Library General Public License also called this License Each licensee is addressed as vou A library means a collection of software functions and or data prepared so as to be conve niently linked with application programs which use some of those functions and data to form executables The Library below refers to any such software library or work which has been distributed under these terms A work based on the Library means either the Library or any derivative work under copyright law that is to say a
112. s itself so that client functions cannot corrupt this state While no simple validation technique can assure that all operations perform correctly calls to OK can at least verify that operations do not corrupt representations For example for String a b c a b c 3 a call to a OK will guarantee that a is a valid String but does not guarantee that it contains the concatenation of b c However given that a is known to be valid it is possible to further verify its properties for example via a after b c amp amp a before c b In other words OK generally checks only those internal representation properties that are otherwise inaccessible to users of the class Other class operations are often useful for further validation Failed calls to OK call a class s error method if one exists else directly call abort Failure indicates an implementation error that should be reported With only rare exceptions the internal support functions for a class never themselves call OK although many of the test files in the distribution call OK extensively Verification of representational invariants can sometimes be very time consuming for complicated data structures 22 User s Guide to the GNU C Class Library Chapter 6 Introduction to container class prototypes 23 6 Introduction to container class prototypes As a temporary mechanism enabling the support of generic classes the GNU C Library distribution con
113. s z to x with the first letter of each word set to uppercase and all others to lowercase setting z to Hello x reverse x upcase x downcase x capitalize in place self modifying versions of the above 62 User s Guide to the GNU C Class Library 17 7 Reading Writing and Conversion cout lt lt x writes out x cout lt lt x at 2 3 writes out the substring Ilo cin gt gt x reads a whitespace bounded string into x x length returns the length of String x 5 in this case s const char x can be used to extract the char char array This coercion is useful for sending a String as an argument to any function expecting a const char argument like atoi and File open This operator must be used with care since the conversion returns a pointer to String internals without copying the characters The resulting char is only valid until the next String operation and you must not modify it The conversion is defined to return a const value so that GNU C will produce warning and or error messages if changes are attempted Chapter 18 The Integer class 63 18 The Integer class The Integer class provides multiple precision integer arithmetic facilities Some representation details are discussed in the Representation section Integers may be up to b 1 lt lt b 1 bits long where b is the number of bits per short typically 1048560 bits when b 16 The implementation assumes that a long
114. so compile or link a work that uses the Library with the Library to produce a work containing portions of the Library and distribute that work under terms of your choice provided that the terms permit modification of the work for the customer s own use and reverse engineering for debugging such modifications User s Guide to the GNU C Class Library You must give prominent notice with each copy of the work that the Library is used in it and that the Library and its use are covered by this License You must supply a copy of this License If the work during execution displays copyright notices you must include the copyright notice for the Library among them as well as a reference directing the user to the copy of this License Also you must do one of these things a Accompany the work with the complete corresponding machine readable source code for the Library including whatever changes were used in the work which must be distributed under Sections 1 and 2 above and if the work is an executable linked with the Library with the complete machine readable work that uses the Library as object code and or source code so that the user can modify the Library and then relink to produce a modified executable containing the modified Library It is understood that the user who changes the contents of definitions files in the Library will not necessarily be able to recompile the application to use the modified definitions b Ac
115. ss commonly useful fast default 0 fast may be set to true 1 if the Regex should be fast compiled This causes an additional compilation step that is generally worthwhile if the Regex will be used many times bufsize default max 40 length of the string This is an estimate of the size of the internal compiled expression Set it to a larger value if you know that the expression will require a lot of space If you do not know do not worry realloc is used if necessary transtable default none 0 The address of a byte translation table a char 256 that translates each character before matching As a convenience several Regexes are predefined and usable in any program Here are their declarations from String h extern Regex RXwhite C n t extern Regex RXint 0 9 extern Regex RXdouble 7 CA CLO 9 7 0 9J NVDONW I VC10 9T VOM WAN 0 97 4 V Chapter 17 The String class 57 LeE o 9 extern Regex RXalpha A Za z extern Regex RXlowercase a z extern Regex RXuppercase A Z extern Regex RXalphanum 0 9A Za z extern Regex RXidentifier A Za z_ A Za z0 9_ 17 2 Examples Most String class capabilities are best shown via example The examples below use the following declarations String x Hello String y world String n 123 String z chart s String lft mid rgt Regex
116. t returns a reference to the front of deque d rear returns a reference to the rear of the deque d del_front deletes but does not return the front of deque d del rear deletes but does not return the rear of the deque d clear removes all elements from the deque 112 User s Guide to the GNU C Class Library Chapter 33 Priority Queue class prototypes 113 33 Priority Queue class prototypes Priority queues maintain collections of objects arranged for fast access to the least element Several prototype implementations of priority queues are supported XPPQs SplayPQs PHPQs All PQ c implement 2 ary heaps via XPlexes implement PQs via Sleator and Tarjan s JACM 1985 splay trees The algorithms use a version of simple top down splaying described on page 669 of the article The simple splay mechanism for priority queue functions is loosely based on the one used by D Jones in the C splay tree functions available from volume 14 of the uunet uu net archives implement pairing heaps as described by Fredman and Sedgewick in Algorithmica Vol 1 p111 129 Storage for heap elements is managed via an internal freelist technique The constructor allows an initial capacity estimate for freelist space The storage is automatically expanded if necessary to hold new items The deletion technique is a fast lazy deletion strategy that marks items as deleted without reclaiming space until the ite
117. t invoking the handler short amp mantissa a long amp mantissa b return a pow 2 15 or b pow 2 31 as an integer These are returned by reference to enable manual data manipulation double value a double value b return a or b as floating point numbers Chapter 22 Classes for Bit manipulation 73 22 Classes for Bit manipulation libg provides several different classes supporting the use and manipulation of collections of bits in different ways e Class Integer provides integer semantics It supports manipulation of bits in ways that are often useful when treating bit arrays as numerical integer quantities This class is described elsewhere e Class BitSet provides set semantics It supports operations useful when treating collections of bits as representing potentially infinite sets of integers e Class BitSet32 supports fixed length BitSets holding exactly 32 bits e Class BitSet256 supports fixed length BitSets holding exactly 256 bits e Class BitString provides string or vector semantics It supports operations useful when treating collections of bits as strings of zeros and ones These classes also differ in the following ways e BitSets are logically infinite Their space is dynamically altered to adjust to the smallest number of consecutive bits actually required to represent the sets Integers also have this property BitStrings are logically finite but their sizes
118. t of a setting a to 00011110 a clear clears all bits of a a set sets all bits of a a invert 0 complements the Oth bit of a setting a to 10011110 a set 0 1 sets the Oth through 1st bits of a setting a to 110111110 The two argument versions of clear and invert are similar a test 3 returns true if the 3rd bit of a is set a test 3 5 returns true if any of bits 3 through 5 are set int i a 3 a 3 0 The subscript operator allows bits to be inspected and changed via standard subscript semantics using a friend class BitSetBit The use of the subscript operator afi rather than a test i requires somewhat greater overhead a first 1 or a first returns the index of the first set bit of a 2 in this case or 1 if no bits are set a first 0 returns the index of the first clear bit of a 0 in this case or 1 if no bits are clear a next 2 1 or a next 2 returns the index of the next bit after position 2 that is set 3 in this case or 1 first and next may be used as iterators as in for int i a first i gt 0 i a next i a last 1 returns the index of the rightmost set bit or 1 if there or no set bits or all set bits 76 User s Guide to the GNU C Class Library a prev 3 0 returns the index of the previous clear bit before position 3 a count 1 returns the number of set bits in a or 1 if there are an infinite number a virtual bit returns the trailing infinitely
119. tains a directory g include of files designed to serve as the basis for generating container classes of specified elements These files can be used to generate h and cc files in the current directory via a supplied shell script program that performs simple textual substitution to create specific classes While these classes are generated independently and thus share no code it is possible to create versions that do share code among subclasses For example using typedef void ent and then generating a entList class other derived classes could be created using the void coercion method described in Stroustrup pp204 210 This very simple class generation facility is useful enough to serve current purposes but will be replaced with a more coherent mechanism for handling C generics in a way that minimally disrupts current usage Without knowing exactly when or how parametric classes might be added to the C language provision of this simplest possible mechanism textual substitution appears to be the safest strategy although it does require certain redundancies and awkward constructions Specific classes may be generated via the genclass shell script program This program has arguments specifying the kinds of base types s to be used Specifying base types requires two arguments The first is the name of the base type which may be any named type like int or String Only named types are supported things like int
120. tdscr attaches w to the default curses library standard screen window CursesWindow w int lines int cols int begin_y int begin_x attaches to an allocated curses window with the indicated size and screen position CursesWindow sub CursesWindow amp w int 1 int c int by int bx char ar a attaches to a subwindow of w created via the curses subwin command If ar is sent as r the origin by bx is relative to the parent window else it is absolute The class maintains a static counter that is used in order to automatically call the curses library initscr and endscr functions at the proper times These need not and should not be called manually CursesWindows maintain a tree of their subwindows Upon destruction of a CursesWindow all of their subwindows are also invalidated if they had not previously been destroyed 88 User s Guide to the GNU C Class Library It is possible to traverse trees of subwindows via the following member functions CursesWindow w parent returns a pointer to the parent of the subwindow or 0 if there is none CursesWindow w child returns the first child subwindow of the window or 0 if there is none CursesWindow w sibling returns the next sibling of the subwindow or 0 if there is none For example to call some function visit for all subwindows of a window you could write void traverse CursesWindow amp w visit w if w child 0 traverse w child
121. ter and sometimes keeping them and sometimes not They seem especially useful in any parsing application One of the test files demonstrates usage A brief summary grow places something on the obstack without committing to wrap it up as a single entity yet finish wraps up a constructed object as a single entity and returns the pointer to its start address copy places things on the obstack and does wrap them up copy is always equivalent to first grow then finish free deletes something and anything else put on the obstack since its creation The other functions are less commonly needed blank is like grow except it just grows the space by size units without placing anything into this space alloc is like blank but it wraps up the object and returns its starting address chunk_size base next_free alignment_mask size room returns the appropriate class variables grow_fast places a character on the obstack without checking if there is enough room blank_fast like blank but without checking if there is enough room shrink int n shrink the current chunk by n bytes contains void addr returns true if the Obstack holds the address addr 50 User s Guide to the GNU C Class Library Here is a lightly edited version of the original C documentation These functions operate a stack of objects Each object starts life small and may grow to maturity Consider building a word syllable by syllable An object c
122. that correspond to 0 bits in the mask are ignored The mask may be shorter than the pattern in which case trailing mask bits are assumed to be 0 The pattern and mask are both public variables and may be individually subjected to other bit operations Converting to char and printing atoBitString atoBitPattern printon ostream lt lt are also as in BitSets except that no virtual bit is used and an X in a BitPattern means that the pattern bit is masked out The following features are unique to BitStrings Assume declarations of BitString a atoBitString 01010110 and b atoBitSTring 1101 a b c Sets a to the concatenation of b and c a b 0 a b 1 sets a to b appended with a zero one at b appends b to a a 0 a 1 appends a zero one to a a lt lt 2 a lt lt 2 return a with 2 zeros prepended setting a to 0001010110 Note the necessary confusion of lt lt and gt gt operators For consistency with the integer versions lt lt shifts low bits to high even though they are printed low bits first 78 a gt gt 3 a gt gt 3 User s Guide to the GNU C Class Library return a with the first 3 bits deleted setting a to 10110 a left_trim 0 deletes all 0 bits on the left of a setting a to 1010110 a right trim 0 deletes all trailing 0 bits of a setting a to 0101011 cat x y Z A faster way to say z diff x y z A faster way to say z and x y Z A f
123. udo generic classes and must be generated via the genclass utility Four subclasses of Plexes are supported A FPlex is a Plex that may only grow or shrink within declared bounds an XPlex may dynamically grow or shrink without bounds an RPlex is the same as an XPlex but better supports indexing with poor locality of reference a MPlex may grow or shrink and additionally allows the logical deletion and restoration of elements Because these classes are virtual subclasses of the abstract class Plex it is possible to write user code such as void f Plex amp a that operates on any kind of Plex However as with nearly any virtual class specifying the particular Plex class being used results in more efficient code Plexes are implemented as a linked list of IChunks Each chunk contains a part of the array Chunk sizes may be specified within Plex constructors Default versions also exist that use a define d default Plexes grow by filling unused space in existing chunks if possible else except for FPlexes by adding another chunk Whenever Plexes grow by a new chunk the default element constructors i e those which take no arguments for all chunk elements are called at once When Plexes shrink destructors for the elements are not called until an entire chunk is freed For this reason Plexes like C arrays should only be used for elements with default constructors and destructors that have no side effects 102 User s Guide t
124. urrently the following subclasses are provided 23 5 Binomial The binomial distribution models successfully drawing items from a pool The first parameter to the constructor n is the number of items in the pool and the second parameter u is the probability of each item being successfully drawn The member asDouble returns the number of samples drawn from the pool Although it is not checked it is assumed that n gt 0 and O lt u lt 1 The remaining members allow you to read and set the parameters 23 6 Erlang The Erlang class implements an Erlang distribution with mean mean and variance variance 23 7 Geometric The Geometric class implements a discrete geometric distribution The first parameter to the constructor mean is the mean of the distribution Although it is not checked it is assumed that O lt mean lt 1 Geometric returns the number of uniform random samples that were drawn before the sample was larger than mean This quantity is always greater than zero 82 User s Guide to the GNU C Class Library 23 8 HyperGeometric The HyperGeometric class implements the hypergeometric distribution The first parameter to the constructor mean is the mean and the second variance is the variance The remaining members allow you to inspect and change the mean and variance 23 9 NegativeExpntl The NegativeExpntl class implements the negative exponential distribution The first param eter to the constructor is
125. way to say x Z y x y prepend x A faster way to say y X y Chapter 17 The String class 61 z replicate x 3 sets z to HelloHelloHello z join words 3 sets z to the concatenation of the first 3 Strings in String array words each separated by setting z to a b c in this case The last argument may be or 0 indicating no separation 17 6 Other manipulations z this string has five words i split z words 10 RXwhite sets up to 10 elements of String array words to the parts of z separated by whitespace and returns the number of parts actually encountered 5 in this case Here words 0 this words 1 string etc The last argument may be any of the usual If there is no match all of z ends up in words 0 The words array is not dynamically created by split int nmatches x gsub 1 11 substitutes all original occurrences of with Il setting x to Hellllo The first argument may be any of the usual including Regex If the second argument is or 0 all occurrences are deleted gsub returns the number of matches that were replaced Z x y z del loworl deletes the leftmost occurrence of loworl in z setting z to Held z reverse x sets z to the reverse of x or olleH Z upcase x sets z to x with all letters set to uppercase setting z to HELLO z downcase x sets z to x with all letters set to lowercase setting z to hello z capitalize x set
126. x specifies the default contents i e the contents of an otherwise uninitialized location The second version specifying initial capacity is allowed for Maps with an initial capacity argument 122 User s Guide to the GNU C Class Library d empty returns true if d contains no items d length returns the number of items in d d k returns a reference to the contents of item with key k If no such item exists it is installed with the default contents Thus d k x installs x and x d k retrieves it d contains k returns true if an item with key field k exists in d d del k deletes the item with key k d clear deletes all items from the table x d dfltQ returns the default contents k d key ind returns a reference to the key at Pix ind x d contents ind returns a reference to the contents at Pix ind ind d first returns the Pix of the first element in d or 0 if d is empty d next ind advances ind to the next element or 0 if there are no more ind d seek k returns the Pix of element with key k or 0 if k is not in d Chapter 37 C version of the GNU getopt function 123 37 C version of the GNU getopt function The GetOpt class provides an efficient and structured mechanism for processing command line options from an application program The sample program fragment below illustrates a typical use of the GetOpt class for some hypothetical application program include lt stdio
127. x i p undel_Pix pix logically undeletes p i p pix p del_low p del_high Delete the lowest highest undeleted element resetting the logical bounds of the plex to the next lowest highest undeleted index Thus MPlex dellow and del_high may shrink the bounds of the plex by more than one index p adjust_bounds Resets the low and high bounds of the Plex to the indexes of the lowest and highest actual undeleted elements int i p add x Adds x in an unused index if possible else performs add_high p count returns the number of valid undeleted elements p available returns the number of available deleted indices int i p unused_index returns the index of some deleted element if one exists else triggers an error An unused element may be reused via undel pix p unused_Pix returns the pix of some deleted element if one exists else 0 An unused element may be reused via undel 106 User s Guide to the GNU C Class Library Chapter 30 Stacks 107 30 Stacks Stacks are declared as an abstract class They are currently implemented in any of three ways VStack implement fixed sized stacks via arrays XPStack implement dynamically sized stacks via XPlexes SLStack implement dynamically size stacks via linked lists All possess the same capabilities They differ only in constructors VStack constructors require a fixed maximum capacity argument XPStack constructors optionally t
128. y charge a fee for the physical act of transferring a copy and you may at your option offer warranty protection in exchange for a fee You may modify your copy or copies of the Library or any portion of it thus forming a work based on the Library and copy and distribute such modifications or work under the terms of Section 1 above provided that you also meet all of these conditions a The modified work must itself be a software library b You must cause the files modified to carry prominent notices stating that you changed the files and the date of any change c You must cause the whole of the work to be licensed at no charge to all third parties under the terms of this License d If a facility in the modified Library refers to a function or a table of data to be supplied by an application program that uses the facility other than as an argument passed when the facility is invoked then you must make a good faith effort to ensure that in the event an application does not supply such function or table the facility still operates and performs whatever part of its purpose remains meaningful For example a function in a library to compute square roots has a purpose that is entirely well defined independent of the application Therefore Subsection 2d requires that any application supplied function or table used by this function must be optional if the application does not supply it the square root function must still compute squar

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