Chinese Translation of the C FAQ

Transcription

1 C Steve Summit, 0.9.3, c 2005

2

3 C FAQ ( ) Steve Summit The English version of this FAQ list is Copyright by Steve Summit. Content from the book C Programming FAQs: Frequently Asked Questions is made available here by permission of the author and the publisher as a service to the community. It is intended to complement the use of the published text and is protected by international copyright laws. The on-line content may be accessed freely for personal use but may not be republished without permission. HTML PDF c-faq-chn L A TEX Steve Summit (scs@eskimo.com), (sunyun.s@gmail.com, 1 12 ) (zhu.qunying@ gmail.com, L A TEX )

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5 i extern auto typedef struct { char *item; NODEPTR next; } *NODEPTR; C N ,, main() void main() , int f() { char a[] = "Hello, world!";} char *p = malloc(10); char a[] = "string literal"; char *p = "string literal"; p[i], , struct x1 {... }; typedef struct {... } x2; struct x {... }; x thestruct; C? C... 7 i

6 ii 2.6 : struct name { int namelen; char namestr[1];}; namestr / / ,,? sizeof,? , core dump #define : a[i] = i++; , int i=7; printf("%d\n", i++ * i++); 49, int i = 3; i = i++;, 3, 4, : a ˆ= b ˆ= a ˆ= b a b && while((c = getchar())!= EOF && c!= \n ) , a[i] = i++; a[], i 1, i i , ++i i int a = 100, b = 100; long int c = a * b; ((condition)? a : b) = complicated expression;

7 iii , char *p; *p = malloc(10); *p++ p p char * int, ((int *)p)++; , void f(int *ip) { static int dummy = 5; ip = &dummy;} : int *ip; f(ip); void**, extern int f(int *); int f(&5); C int char *, (null) if(p) NULL, , NULL NULL #define NULL ((char *)0) NULL NULL 0, NULL,, NULL ( 0) #define Nullptr(type) (type *) NULL 0, (null) , ,, 26

8 iv char a[6], extern char *a char a[ ] char *a , C , , , , 5["abcdef"] C , arr, arr &arr : int realarray[10]; int *array = &realarray[-1]; array , , sizeof char *answer; printf("type something:\n"); gets(answer); printf("you typed \"%s\"\n", answer); strcat(). char *s1 = "Hello, "; char *s2 = "world!"; char *s3 = strcat(s1, s2); strcat char * ( ) char *p; strcpy(p, "abc"); ,,,

9 v malloc(), : malloc malloc(), void * int * char *p = malloc(strlen(s) + 1); strcpy(p, s); malloc((strlen(s) + 1) * sizeof(char)) malloc , : double *array = malloc(300 * 300 * sizeof( double )); malloc() null,,, malloc(), PC 8 640K , malloc malloc() bug , free() (, ) malloc(), free() ,, ,, free() malloc, realloc() calloc() malloc() calloc free() calloc(), cfree() alloca() strcat(string,! ); char *string;... if(string == "value") { /* string matches value */... }

10 vi 8.3 char a[] = "Hello, world!"; char a[14]; a = "Hello, world!"; ( ), : sizeof( a ) 2 1 (, sizeof(char)) C #define enum true false C, TRUE p, if(p) C : #define begin { #define end } ,.c,.h (.h ) #include <> #include "" , , , #if sizeof #if #include #ifdef typdef #ifdef #if , #ifdef #include #ifdef,

11 vii 10.18, #define Paste(a, b) a/**/b #define TRACE(n) printf("trace: %d\n", n) TRACE(count); printf("trace: %d\count", count); #, , ANSI/ISO C ANSI C ANSI extern int func(float); int func(x) float x; { extern int f(struct x *p); x : const int n = 5; int a[n]; , const char *p char * const p const char ** char ** main() main() void, main main() envp main() void, exit() return, / void main() C void main() main(), exit(status) status ANSI #, warning: macro replacement within a string literal #ifdef #pragma, #pragma once.. 59

12 viii a[3] = "abc"; void* memcpy() memmove() malloc(0) ANSI ASNI/ISO ANSI C ANSI C, ANSI Frobozz Magic C ANSI, gcc (implementation-defin-ed) (unspecified) (undefined) , , ANSI i = i++, ANSI, char c; while((c = getchar())!= EOF) EOF, EOF while(!feof(infp)) { fgets(buf, MAXLINE, infp); fputs(buf, outfp); } , printf % \%, printf %lf, scanf() %lf, printf() %f size t, long, printf printf, %8d scanf("%d", i) char s[30]; scanf("%s", s); &

13 ix double d; scanf("%f", &d); scanf() %d\n scanf, scanf %d, gets(), gets() , scanf(), scanf() sprintf sprintf() gets() printf() errno ENOTTY fgetops/fsetops ftell/fseek fgetops() fsetops() , fflush(stdin) fflush(), fopen() r+,,, stdin stdout freopen(), stdout ( stdin) , x0a 0x0d, 0x1a, EOF ( atoi ) itoa() strncpy() \ toupper() toupper() tolower() main() argc argv strcmp(), qsort(), qsort(), qsort()

14 x C localtime() time t struct tm, ctime() time t, struct tm time t N , rand() /, rand() % 2, 0, 1, 0, 1, , #inlude , end printf float 3.1, printf , , #include <math.h>, undefined: sin ( sin ) , C <math.h> M PI IEEE NaN C (FFT) ( ) Turbo C, floating point formats not linked ( ) printf(), #include <stdio.h>

15 xi 15.2 %f printf(), float double n long int, printf("%d", n); ANSI printf(), printf() scanf(), scanf() float, va arg(argp, float) va arg() , , ,, main() , main() ,,, : char *p = "hello, worl!"; p[0] = H ; Segmentation violation, Bus error General protection fault C if(!strcmp(s1, s2)), if (0 == x) if (x == 0) extern int func ((int, int));, printf(), (void) (Hungarian Notation) (Indian Hill Style Guide)

16 xii 17.8 goto, malloc ANSI lint ANSI lint C , C C C ANSI/ISO C C BNF YACC C RETURN ,,, , ( comm ) GIF JPEG ,

17 xiii ( ) fopen("c:\ newdir \file.dat", "r") fopen() : "$HOME/.profile" " /.myrcfile" MS-DOS Abort, Retry, Ignore? Too many open files (, C K DGROUP data allocation exceeds 64K (DGROUP 64K), 64K ( ) C (, ) , control-c socket / BIOS ISR TSR , union REGS int86() near far , ANSI! , char *

18 xiv printf() i i = i ,, i/= case ( ) return C C a+++++b C assert() C FORTRAN (C++, BASIC, Pascal, Ada, LISP) Pascal Fortran ( LISP, Ada, awk, C) C C++ C C++ C strcmp,, , (year%4 == 0) : (Duff s Device) C (IOCCC) [K&R1] entry C char lvalue rvalue

19 xv FAQ ( )

20 xvi

21 1 1.1 ( 32, , 767), long, ( ), short, int,,, ( ), ; 12.1,, C99 <inttypes.h> typedef,, 20.3 C, : [K&R1, Sec. 2.2 p. 34]; [K&R2, Sec. 2.2 p. 36, Sec. A4.2 pp , Sec. B11 p. 257]; [ISO, Sec , Sec ]; [H&S, Secs. 5.1,5.2 pp ] C99 long long, 64, longlong, , : [C9X, Sec , Sec ] 1

22 , ( ), ( ).c, (.h),,.c, : ANSI C, ANSI Unix, ; ANSI C, DEFINE(int, i);,,,.c :, : [K&R1, Sec. 4.5 pp. 76-7]; [K&R2, Sec. 4.4 pp. 80-1]; [ISO, Sec , Sec. 6.7, Sec , Sec. G.5.11]; [Rationale, Sec ]; [H&S, Sec. 4.8 pp , Sec p. 267]; [CT&P, Sec. 4.2 pp ]. 1.4 extern, extern int f(); int f(); : [ISO, Sec , Sec ]; [Rationale, Sec ]; [H&S, Secs. 4.3,4.3.1 pp. 75-6]. 1.5 auto : [K&R1, Sec. A8.1 p. 193]; [ISO, Sec , Sec ;]; [H&S, Sec. 4.3 p. 75, Sec p. 76].

23 typedef struct { char *item; NODEPTR next; } *NODEPTR; C C ; [K&R2, 6.5 ] NODEPTR next typedef, ( struct node ), next struct node *, typedef, : struct node { char *item; struct node *next; }; typedef struct node *NODEPTR; typedef, 2.1 : [K&R1, Sec. 6.5 p. 101]; [K&R2, Sec. 6.5 p. 139]; [ISO, Sec , Sec ]; [H&S, Sec pp ] 1.7 N 3 : 1. char *(*(*a[n])())(); 2. typedef : typedef char *pc; /* */ typedef pc fpc(); /* */ typedef fpc *pfpc; /* */ typedef pfpc fpfpc(); /* */ typedef fpfpc *pfpfpc; /* */ pfpfpc a[n]; /* */ 3. cdecl, C C : cdecl> declare a as array of pointer to function returning pointer to function returning pointer to char char *(*(*a[])())(), cdecl, ( ) 18.1

24 1 4 C C ( ), cdecl : [K&R2, Sec p. 122]; [ISO, Sec. 6.5ff (esp. Sec )]; [H&S, Sec. 4.5 pp , Sec pp ] 1.8,, ( ) (int) ( ), ( ) : [K&R1, Sec. 4.2 p. 70]; [K&R2, Sec. 4.2 p. 72]; [ISO, Sec ]; [H&S, Sec. 4.7 p. 101]. 1.9 main() void main() ( ) 1.10, (, ), =0,, 0.0 (, 5 ) (, ), ( );, malloc() realloc(), calloc(), ( ) : [K&R1, Sec. 4.9 pp. 82-4]; [K&R2, Sec. 4.9 pp ]; [ISO, Sec , Sec , Sec ]; [H&S, Sec pp. 72-3, Sec. 4.6 pp. 92-3, Sec pp. 94-5, Sec p. 96, Sec p. 386.]

25 int f() { char a[] = "Hello, world!";} ANSI, (automatic aggregates, ) char *p = malloc(10); ( ) 1.13 char a[] = "string literal"; char *p = "string literal"; p[i], ( char a[] ),,,,, ( 6 ), p, : [K&R2, Sec. 5.5 p. 104]; [ISO, Sec , Sec ]; [Rationale, Sec ]; [H&S, Sec pp. 31-2] 1.14, extern int func(); int (*fp)() = func;, (, ), ( ) ( )

26 1 6

27 2 2.1 struct x1 {... }; typedef struct {... } x2; ; struct x1, x2,, struct 2.2 struct x {... }; x thestruct; C C C? ( ), ( ) 2.5 C,,, (, ),,,, C++ 7

28 : struct name { int namelen; char namestr[1];}; namestr, Dennis Ritchie C C,, ; :... char namestr[maxsize]; MAXSIZE name,,, C99, : [Rationale, Sec ]; [C9X, Sec ] 2.7 (, == ), C ( 2.10) ;, : [K&R2, Sec. 6.2 p. 129]; [Rationale, Sec ]; [H&S, Sec p. 133] 2.8 C ; C99 (compound literals);, plotpoint(), plotpoint((struct point){1, 2}); (designated initializers) (C99 ), : plotpoint((struct point){.x=1,.y=2}); 4.6 : [C9X, Sec , Sec ]

29 / / fwrite() : fwrite(&somestruct, sizeof somestruct, 1, fp); fread() ( ),,,,, b ; 12.30, ( ), : [H&S, Sec p. 381] 2.10,,?,,, ( ) (, char ), 2 4 ( #pragma; 11.21), 20.3 : [K&R2, Sec. 6.4 p. 138]; [H&S, Sec p. 135] 2.11 sizeof,?,,, sizeof 2.10 : [H&S, Sec pp ] 2.12 ANSI C <stddef.h> offsetof(), offsetof(struct s, f) f s,, : 292-3] #define offsetof(type, f) ((size_t) \ ((char *)&((type *)0)->f - (char *)(type *)0)) 100% ; : [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec pp.

30 offsetof() ( 2.12) structp, f, offsetf, f : *(int *)((char *)structp + offsetf) = value; 2.14, core dump : struct list { char *item; struct list *next; } /* main */ main(argc, argv) {... } main(),,,, main(), (, C ) : [CT&P, Sec. 2.3 pp. 21-2] 2.15 ANSI C, C99, : [K&R2, Sec. 6.8 pp ]; [ISO, Sec ]; [C9X, Sec ]; [H&S, Sec p. 100] 2.16 #define C, : ;, ;,, ; : [K&R2, Sec. 2.3 p. 39, Sec. A4.2 p. 196]; [ISO, Sec , Sec , Sec , Annex F]; [H&S, Sec. 5.5 pp , Sec p. 153]

31 ,,,

32 2 12

33 3 3.1 : a[i] = i++; i++ i i,, ( a[i] ) (, K&R, C, : [K&R1, Sec. 2.12]; [K&R2, Sec. 2.12]; [ISO, Sec. 6.3]; [H&S, Sec pp ] 3.2, int i=7; printf("%d\n", i++ * i++); 49, , ( ANSI C,, 3.7), (,, ; 3.7, ) ( C ); K&R,, : [K&R1, Sec p. 50]; [K&R2, Sec p. 54]; [ISO, Sec. 6.3]; [H&S, Sec pp ]; [CT&P, Sec. 3.7 p. 47]; [PCS, Sec. 9.5 pp ] 13

34 int i = 3; i = i++;, 3, 4, ; 3.1, , i++ ++i i+1 i 1, i=i+1, i+=1, i++ ++i,, : a ˆ= b ˆ= a ˆ= b a b a,, : int a = 123, b = 7654; a ^= b ^= a ^= b; SCO C (icc) b 123, a ,. f() + g() * h(),, : [K&R1, Sec p. 49, Sec. A.7 p]; [K&R2, Sec pp. 52-3, Sec. A.7 p. 200.] 3.6 && while((c = getchar())!= EOF && c!= \n ) : (, && ),,, (? : ) ( 3.7) : [K&R1, Sec. 2.6 p. 38, Secs. A pp ]; [K&R2, Sec. 2.6 p. 41, Secs. A pp ]; [ISO, Sec , Sec , Sec ]; [H&S, Sec. 7.7 pp , Sec. 7.8 pp , Sec p. 229]; [CT&P, Sec. 3.7 pp. 46-7]

35 ( &&? :, ),, ANSI/ISO C :,, i = i+1, a[i] = i++ ( 3.1) 3.8 : [ISO, Sec , Sec. 6.3, Sec. 6.6, Annex C]; [Rationale, Sec ]; [H&S, Sec pp ] 3.8, a[i] = i++; a[], i 1,, 3.2, 3.3, i i++ C, : ++i i, ; i++ i, 3.10, ++i i++,,, C++, int a = 100, b = 100; long int c = a * b; C, int, long c, long : long int c = (long int)a * b;

36 3 16, (long int)(a * b),, : [K&R1, Sec. 2.7 p. 41]; [K&R2, Sec. 2.7 p. 44]; [ISO, Sec ]; [H&S,, ]; [CT&P, Sec. 3.9 pp ] 3.12 ((condition)? a : b) = complicated expression;? :,,,,? :, : *((condition)? &a : &b) = complicated_expression; : [ISO, Sec ]; [H&S, Sec. 7.1 pp ]

37 4 4.1, char *p; *p = malloc(10); p, *p, (, ), : p = malloc(10);, * : *p = H ; 1.7, 7.1, : [CT&P, Sec. 3.1 p. 28] 4.2 *p++ p p ++ --, *p++ *(p++), p p p, (*p)++, ++*p : [K&R1, Sec. 5.1 p. 91]; [K&R2, Sec. 5.1 p. 95]; [ISO, Sec , Sec ]; [H&S, Sec pp , Sec. 7.5 p. 193, Secs ,7.5.8 pp ] 4.3 char * int, ((int *)p)++; C,, ;, (rvalue), ++ (,, ) : p = (char *)((int *)p + 1);, p char *, p += sizeof(int);,,, : [K&R2, Sec. A7.5 p. 205]; [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec. 7.1 pp ] 17

38 , void f(int *ip) { static int dummy = 5; ip = &dummy;} : int *ip; f(ip); C, ( ), void**, C void*,, ;, void* void**, 4.6 extern int f(int *); int f(&5); C99, : f((int[]){5}); C99, ;, : int five = 5; f(&five); 2.8, C, C,, &, ( 6.4 ), C C++, : [K&R1, Sec. 1.8 pp. 24-5, Sec. 5.2 pp. 91-3]; [K&R2, Sec. 1.8 pp. 27-8, Sec. 5.2 pp. 95-7]; [ISO, Sec ]; [H&S, Sec. 9.5 pp ]

39 , * ( ) : int r, func(), (*fp)() = func; r = (*fp)();, (, 1.14) fp r = fp(); ANSI C, *, 1.14 : [K&R1, Sec p. 116]; [K&R2, Sec p. 120]; [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec. 5.8 p. 147, Sec p. 190] 4.9 int char *,,, 13.1, 8.4, 19.29

40 4 20

41 5 (null) 5.1,,, &, malloc(),, malloc(), : ; ,,,, ( ) [K&R1, Sec. 5.4 pp. 97-8]; [K&R2, Sec. 5.4 p. 102]; [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec pp ] 5.2, 0,,, 0 char *p = 0; if(p!= 0) 5.3,, 0, 0, Unix execl execl("/bin/sh", "sh", "-c", "date", (char *)0); (char *),, 0 ( Unix ) 21

42 5 (null) 22,,,, 0 ( 15.3) : 0: :, [K&R1, Sec. A7.7 p. 190, Sec. A7.14 p. 192]; [K&R2, Sec. A7.10 p. 207, Sec. A7.17 p. 209]; [ISO, Sec ]; [H&S, Sec p. 95, Sec p. 171] 5.3 if(p) 0 C, 0,, if(expr) expr, if((expr)!= 0) p expr if(p) if(p!= 0), 0, ;,! :!expr (expr) 0:1 ((expr) == 0) if(!p) if(p == 0) if(p),, ( ; 17.8) 9.2 [K&R2, Sec. A7.4.7 p. 204]; [ISO, Sec , Sec , Sec , Sec , Sec , Sec , Sec ]; [H&S, Sec p. 122]

43 5 (null) NULL,, 0 NULL ( <stdio.h> ), 0 ((void *)0) ( 5.6) 0 0 NULL NULL ; NULL 0, 0,, NULL ( 0 ) NULL ( NULL 0 ) NULL ; 5.7 [K&R1, Sec. 5.4 pp. 97-8]; [K&R2, Sec. 5.4 p. 102]; [ISO, Sec , Sec ]; [Rationale, Sec ]; [H&S, Sec p. 122, Sec p. 292] 5.5, NULL : 0 ( 0; 5.4), 0 NULL,, 0 NULL [ISO, Sec ]; [Rationale, Sec ] 5.6 NULL #define NULL ((char *)0) NULL,, NULL, ( ), FILE *fp = NULL;, ANSI C NULL #define NULL ((void *)0) (, ), NULL (, ASCII NUL ; 5.7), ANSI ( ; 5.2), [Rationale, Sec ]

44 5 (null) NULL 0, NULL, 0,, 0 ( ) C, NULL 0, 0 NULL ( 0 ), ; ( ) 0 0 0, NULL, (, ANSI NULL ((void *)0),, ASCII (NUL) NULL, #define NUL \0 [K&R1, Sec. 5.4 pp. 97-8]; [K&R2, Sec. 5.4 p. 102] 5.8 NULL,, NULL ( 0) ( NULL, ), NULL 0 0 ( ) NULL #define Nullptr(type) (type *)0,, ; NULL 0, (null) null NULL, : 1., ( ),, C,

45 5 (null) 25 3., 0 ( 5.2) 4. NULL, 0 ( 5.4) 5. ASCII (NUL),,, ; 6. (null string), ("") C, ( \0 ),, ( null pointer, ), 0 3, NULL C ( ) (NULL) if(p == 0) p, 0, ( 5.10 ) C ( Pascal, nil ) nil,, C nil 0,, 0, 0, 0, 5.12 : 1., 0 NULL 2. 0 NULL,, ( ), (, 2 ; ) ,

46 5 (null) , 0,,,,, ( calloc() ; 7.26), int ( 5.11, nil, 0 ) 5.14,, PL/I, Prime , 0 0, 0 C, TCNP ( C ) C Prime (char *) (int *) Data General Eclipse MV ( ), C char * void *, Honeywell-Bull ( ) CDC Cyber 180 (ring), 48 ( 11 ) 0xB CDC 1,, HP 3000 ;, char * void * Symbolics Lisp, ; <NIL, 0> ( <, > ) C, 8086 (PC ) 16 32, 64 Cray 48 int *; char * 16 [K&R1, Sec. A14.4 p. 211] 5.15, MS-DOS, ( 0 ) 16.7

47 6 6.1 char a[6], extern char *a, extern char * T T extern char a[ ] 64-5] [ISO, Sec ]; [CT&P, Sec. 3.3 pp. 33-4, Sec. 4.5 pp. 6.2 char a[ ] char *a ( 6.4) char a[6] 6, a, a, 6 char *p,, p :, ( ) char a[] = "hello"; char *p = "world"; : a: h e l l o \ p: *======> w o r l d \ x, x[3], a[3], a 3,. p[3], p,, 3, a[3] a ( ) 3, p[3] p 3., a[3] p[3] l, a p 27

48 6 28, 1.13 [K&R2, Sec. 5.5 p. 104]; [CT&P, Sec. 4.5 pp. 64-5] 6.3, C C,, : T ( ); T,,, &a[0], sizeof &,, a[i],, p[i], 6.2, : p = a; p[3] a[3] [K&R1, Sec. 5.3 pp. 93-6]; [K&R2, Sec. 5.3 p. 99]; [ISO, Sec , Sec , Sec ]; [H&S, Sec p. 124] 6.4,,,, void f(char a[]) {... },,. void f(char *a) {... },, ;,

49 [K&R1, Sec. 5.3 p. 95, Sec. A10.1 p. 205]; [K&R2, Sec. 5.3 p. 100, Sec. A8.6.3 p. 218, Sec. A10.1 p. 226]; [ISO, Sec , Sec , Sec ]; [H&S, Sec. 9.3 p. 271]; [CT&P, Sec. 3.3 pp. 33-4] 6.5, 179] ANSI C, : [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec. 7.1 p. 6.6,, ( malloc), (, ),, ( 6.3),, malloc ( [ ] ) , sizeof ,,, , 5["abcdef"] C, 1, C, a e,, a[e] *((a)+(e)) C, C, : [Rationale, Sec ]; [H&S, Sec p. 124, Sec pp ] 1, 1897, (Virginia),,, Yes, Virginia, there is a Santa Claus, santa/virginia s question.htm

50 , arr, arr &arr C, &arr T, ANSI C, &arr &, C, ( & ) T, 6.3, : [ISO, Sec , Sec ]; [Rationale, Sec ]; [H&S, Sec p. 198] 6.10,,, T T ( 6.3), ;,,, 6.15, int (*ap)[n]; N ( 1.7), N,,, 6.9 : [ISO, Sec ] 6.11 ( 6.3), malloc #include <stdlib.h> int *dynarray; dynarray = malloc(10 * sizeof(int)); ( malloc ), dynarry[i] (i 0 9) sizeof , ; C, C99 (VLA), ;

51 6 31, ( gcc ) C99 gcc, malloc(), free() 6.11, 6.13, 6.16, : [ISO, Sec. 6.4, Sec ]; [C9X, Sec ] 6.13, : #include <stdlib.h> int **array1 = malloc(nrows * sizeof(int *)); for(i = 0; i < nrows; i++) array1[i] = malloc(ncolumns * sizeof(int));,, malloc sizeof(*array1) sizeof(**array1) sizeof(int *) sizeof(int),, : int **array2 = malloc(nrows * sizeof(int *)); array2[0] = malloc(nrows * ncolumns * sizeof(int)); for(i = 1; i < nrows; i++) array2[i] = array2[0] + i * ncolumns;, arrayx[i][j] (for 0 <= i <nrows 0 <= j <ncolumns), : int *array3 = malloc(nrows * ncolumns * sizeof(int));,, array3[i * ncolumns + j] i, j,,, 6.16 : int (*array4)[ncolumns] = malloc(nrows * sizeof(*array4));,, ( ; 7.20) , C99 : [C9X, Sec ]

52 : int realarray[10]; int *array = &realarray[-1]; array 1 ( Numerical Recipes in C ), C, ;,, ( ), : [K&R2, Sec. 5.3 p. 100, Sec. 5.4 pp , Sec. A7.7 pp ]; [ISO, Sec ]; [Rationale, Sec ] 6.15, ( 6.3) ( C ),, ; 6.10 : int array[nrows][ncolumns]; f(array); : void f(int a[][ncolumns]) {... } void f(int (*ap)[ncolumns]) /* ap */ {... }, ( );,, NROWS, NCOLUMNS (, ), : [K&R1, Sec p. 110]; [K&R2, Sec. 5.9 p. 113]; [H&S, Sec p. 126] 6.16 [0][0],

53 6 33 void f2(int *aryp, int nrows, int ncolumns) {... array[i][j] is accessed as aryp[i * ncolumns + j]... } 6.15 : f2(&array[0][0], NROWS, NCOLUMNS);,, ANSI C ;, x >= NCOLUMNS, &array[0][0][x] C99, C99, VLA gcc, , 6.17, 6.12 : [ISO, Sec ]; [C9X, Sec ] 6.17 int array[nrows][ncolumns]; int **array1; /* */ int **array2; /* */ int *array3; /* " " */ int (*array4)[ncolumns]; 6.13, void f1a(int a[][ncolumns], int nrows, int ncolumns); void f1b(int (*a)[ncolumns], int nrows, int ncolumns); void f2(int *aryp, int nrows, int ncolumns); void f3(int **pp, int nrows, int ncolumns); f1a() f1b(), f2(), f3() ( ), : f1a(array, NROWS, NCOLUMNS); f1b(array, NROWS, NCOLUMNS); f1a(array4, nrows, NCOLUMNS); f1b(array4, nrows, NCOLUMNS); f2(&array[0][0], NROWS, NCOLUMNS); f2(*array, NROWS, NCOLUMNS); f2(*array2, nrows, ncolumns); f2(array3, nrows, ncolumns); f2(*array4, nrows, NCOLUMNS); f3(array1, nrows, ncolumns); f3(array2, nrows, ncolumns);,, ncolumns NCOLUMNS :

54 6 34 f1a((int (*)[NCOLUMNS])(*array2), nrows, ncolumns); f1a((int (*)[NCOLUMNS])(*array2), nrows, ncolumns); f1b((int (*)[NCOLUMNS])array3, nrows, ncolumns); f1b((int (*)[NCOLUMNS])array3, nrows, ncolumns); f2() &array[0][0] ( *array) ; 6.16,, C,, array1 array2 f3() 6.18, sizeof ( 6.4), : [H&S, Sec p. 195]

55 7 7.1 char *answer; printf("type something:\n"); gets(answer); printf("you typed \"%s\"\n", answer); answer, gets(),,, answer,, answer :,, #include <stdio.h> #include <string.h> char answer[100], *p; printf("type something:\n"); fgets(answer, sizeof answer, stdin); if((p = strchr(answer, \n ))!= NULL) *p = \0 ; printf("you typed \"%s\"\n", answer); fgets() gets(), array 12.20, fgets() gets() \n malloc() answer 7.2 strcat(). char *s1 = "Hello, "; char *s2 = "world!"; char *s3 = strcat(s1, s2); 7.1, C C (, ), malloc() strcat() ;, : char s1[20] = "Hello, "; 35

56 7 36 strcat(), s1, s3 ; strcat(), s1 strcat() : s1,, 1.13 : [CT&P, Sec. 3.2 p. 32] 7.3 strcat char * ( ),,,, Unix ANSI C, ( ) (, ) time() ( 13.10) stat() 7.4 char *p; strcpy(p, "abc");, p, , char *p; (,, ) ;,, sizeof(char*) ,,,, : char *itoa(int n) { char retbuf[20]; /* */ sprintf(retbuf, "%d", n); return retbuf; /* */ }

57 7 37 static char retbuf[20];,, 7.7, : [ISO, Sec ] 7.7 ( 7.6 ),, malloc(), ( ) malloc(), : <stdlib.h> malloc() 1.8 : [H&S, Sec. 4.7 p. 101] 7.9 malloc ANSI/ISO C void *, ( ) ANSI/ISO C,,, malloc() ; 7.8 (,, C++, C C++ void * ) : [H&S, Sec pp ] 7.10 malloc(), void * int * C++ C char *p = malloc(strlen(s) + 1); strcpy(p, s); malloc((strlen(s) + 1) * sizeof(char)) sizeof(char),, sizeof(char) 1, sizeof(char), size t 8.5 : [ISO, Sec ]; [H&S, Sec p. 195]

58 malloc, : [ISO, Sec ] 7.14, : double *array = malloc(300 * 300 * sizeof( double )); malloc() null,,, malloc(), 300 * ,000, sizeof(double) 16 int, size t (malloc() ) 32, int 16, 300 * (300 * sizeof(double)) ( 3.11),, 32, PC 8 640K PC, 640K, MS-DOS , malloc malloc() bug, malloc, malloc ; bug malloc(strlen(s)) strlen(s) + 1, malloc,,, , , malloc(), C

59 7 39, : struct list *listp, *nextp; for(listp = base; listp!= NULL; listp = nextp) { nextp = listp->next; free(listp); } nextp, listp = listp-> next : [K&R2, Sec p. 167]; [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec p. 387]; [CT&P, Sec p. 95] 7.18 free() (, ) free(),,, C 4.4,,,,,, : [ISO, Sec ]; [Rationale, Sec ] 7.19 malloc(), free(),,, malloc(), malloc() free() 7.20,,, free() malloc(), ( ) malloc(), free() malloc() 7.21

60 ,, ANSI/ISO C : [ISO, Sec ] 7.22,, malloc/free, malloc() 7.23 free() malloc/free, 7.24 malloc,, 7.25 realloc() ANSI C, realloc(..., 0),,, realloc() : [ISO, Sec ]; [H&S, Sec p. 388] 7.26 calloc() malloc() calloc free() calloc(), cfree() calloc(m, n) p = malloc(m * n); memset(p, 0, m * n);, ( 5 ) free() calloc() : [ISO, Sec to ]; [H&S, Sec p. 386, Sec p. 386]; [PCS, Sec. 11 pp. 141,142]

61 alloca() alloca(),, alloca alloca(),, fgets(alloca(100), 100, stdin), alloca(),, C99 (VLA), alloca() 7.19 : [Rationale, Sec ]

62 7 42

63 8 8.1 strcat(string,! );, strcat() C, 8.4 ;!, strcat(string, "!"); 1.13, : [CT&P, Sec. 1.5 pp. 9-10] 8.2 char *string;... if(string == "value") { /* string matches value */... } C, C (, ) == string value,,,, strcmp(): if(strcmp(string, "value") == 0) { /* string matches "value" */ } 8.3 char a[] = "Hello, world!"; char a[14]; a = "Hello, world!";, strcpy() : strcpy(a, "Hello, world!"); 1.13,

64 ( ), C, :, 0-9, 0,, : sizeof( a ) 2 1 (, sizeof(char)), C int, sizeof( a ) sizeof(int), C : [ISO, Sec ]; [H&S, Sec p. 29]

65 9 9.1 C #define enum true false C, / ( int, char, int, ) #define true/false, ( ) #define TRUE 1 #define YES 1 #define FALSE 0 #define NO 0 enum bool {false, true}; enum bool {no, yes}; 1 0,, #define TRUE (1==1) #define FALSE (!TRUE) #define Istrue(e) ((e)!= 0), 9.2, C, TRUE 1 1 C,,,, 1 0, if((a == b) == TRUE) ( TRUE 1),, TRUE FALSE TRUE FALSE, ( isupper(), isalpha() ), 1 (, if((a == b) 45

66 9 46 == TRUE) if(a == b), if(((a == b) == TRUE) == TRUE)?) TRUE FALSE ( ),, TRUE FALSE ( NULL), ( ) TRUE FALSE ( YES NO), C TRUE FALSE, : [K&R1, Sec. 2.6 p. 39, Sec. 2.7 p. 41]; [K&R2, Sec. 2.6 p. 42, Sec. 2.7 p. 44, Sec. A7.4.7 p. 204, Sec. A7.9 p. 206]; [ISO, Sec , Sec , Sec , Sec , Sec , Sec , Sec , Sec ]; [H&S, Sec pp , Sec pp , Sec pp , Sec. 7.7 pp , Sec. 7.8 pp , Sec. 8.5 pp , Sec. 8.6 pp ]; What the Tortoise Said to Achilles 9.3 p, if(p). 5.3

67 10 C 10.1 : #define begin { #define end } ,,, ( ) ( ),, ( ), C typeof, 10.3,,, (, ), if/else if else, : #define MACRO(arg1, arg2) do { \ /* declarations */ \ stmt1; \ stmt2; \ /*... */ \ } while(0) /* ; */, 0, lint,,,,, DEBUG() : [H&S, Sec p. 45]; [CT&P, Sec. 6.3 pp. 82-3] 47

68 10 C ,.c,.h (.h ), (.h) : ( #defines) typedef ( 1.4),,.c 1.3,.c,.c : [K&R2, Sec. 4.5 pp. 81-2]; [H&S, Sec p. 267]; [CT&P, Sec. 4.6 pp. 66-7] 10.5, : (Indian Hill Style Guide, 17.7) ; ;, ; makefile, (, ); grep ( tags ), ; : #ifndef HFILENAME_USED #define HFILENAME_USED #endif ; Makefile (, ) 17.8 : [Rationale, Sec ] 10.6 #include <> #include "" <>, ""

69 10 C ; 11.32, <> "", ( ) : [K&R2, Sec. A12.4 p. 231]; [ISO, Sec ]; [H&S, Sec. 3.4 p. 55] 10.8, 2.14, , ,,,,, <stdlib.h> <malloc.h>,,,,. ( 19 ), #if ; #if, : [K&R2, Sec p. 91; ISO Sec ]; [H&S, Sec p. 225]

70 10 C sizeof #if,, ANSI <limits.h>, (configure), ; #include #ifdef #ifdef #define : [ISO, Sec , Sec ]; [H&S, Sec. 3.2 pp. 40-1] typdef #ifdef, ( MY TYPE DEFINED) typdef : [ISO, Sec , Sec ]; [H&S, Sec p. 225] #if (, ) : [ISO, Sec ]; [H&S, Sec p. 225] 10.16, #ifdef #include #ifdef, unifdef, rmifdef scpp (selective C preprocessor) , gcc -E -dm,, Unix, ( unix ) ( ),

71 10 C , #define Paste(a, b) a/**/b ( Reiser),, ANSI ( K&R ), ANSI ##, 52] #define Paste(a, b) a##b : [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec p #define TRACE(n) printf("trace: %d\n", n) TRACE(count); printf("trace: %d\count", count); #, , C,, make(1) C, Unix m , printf() #define DEBUG(args) (printf("debug: "), printf args) if(n!= 0) DEBUG(("n is %d\n", n)); gcc (DEBUG1, DEBUG2, ), :

72 10 C 52 #define DEBUG(args) (printf("debug: "), printf(args)) #define _, DEBUG("i = %d" _ i); C99... ( ), VA ARGS,, ,, #define printf myprintf : [C9X, Sec , Sec ]

73 11 ANSI/ISO C 11.1 ANSI C 1983, (ANSI) X3J11 C, ANSX ANSI C, C++ ( ) ( ) ANSI C C,, ISO/IEC 9899:1990, ( ANSI/ISO [1992]) X3.159 ISO, 1994, 1 (TC1) 40,, 1 (NA1) 50, 1995, TC2,, C99,, C99 ANSI, (Rational),, (PDF) American National Standards Institute 11 W. 42nd St., 13th floor New York, NY USA (+1) Global Engineering Documents 15 Inverness Way E Englewood, CO USA (+1) (800) (U.S. & Canada),, Geneva ISO, : 53

74 11 ANSI/ISO C 54 ISO Sales Case Postale 56 CH-1211 Geneve 20 Switzerland URL comp.std.internat FAQ, Standards.Faq Herbert Schild ANSI C ISO 9899 ; Osborne/McGraw-Hill, ISBN , 40 :, Clive Feather ( ) ANSI ftp://ftp.uu.net/doc/standards/ansi/ X ftp ( 18.18), lysator.liu.se/c/rat/title.html Silicon Press, ISBN C9X ISO/IEC JTC1/SC22/WG14, ( C9X ): liu.se/c/index.html, dmk.com/ 11.4 ANSI extern int func(float); int func(x) float x; {... extern int func(float); int func(x) float x;, C ( ANSI C),,, : int func(float x) {... } extern int func(double);

75 11 ANSI/ISO C 55,,, (char, short int float) 1.8 : [K&R1, Sec. A7.1 p. 186]; [K&R2, Sec. A7.3.2 p. 202]; [ISO, Sec , Sec ]; [Rationale, Sec , Sec ]; [H&S, Sec. 9.2 pp , Sec. 9.4 pp ] 11.5,, 11.4,, : [ISO, Sec , Sec ]; [H&S, Sec pp , Sec pp ] 11.6 extern int f(struct x *p); x C, ( ),, : struct x; x,, x x : [ISO, Sec , Sec , Sec ] 11.7 : const int n = 5; int a[n]; const ; ( ) const C C++, #define ( enum) : [ISO, Sec. 6.4]; [H&S, Secs , pp ] 11.8,

76 11 ANSI/ISO C 56 char *p = "Hello, world!"; p const char *p char * const p const char *p ( char const *p ), ; char * const p ( ),, ; 1.7 : [ISO, Sec ]; [Rationale, Sec ]; [H&S, Sec p. 81] const char ** char ** const-t T ( T ), ( ),, (, (const char **)),, : [ISO, Sec , Sec , Sec ]; [H&S, Sec pp ] main() int main(), int main(void) int main(int argc, char *argv[]) ( argc argv ) : [ISO, Sec , Sec. G.5.1]; [H&S, Sec p. 416]; [CT&P, Sec pp ] main() void, main main() int, exit(), return (, void main(), C ) /

77 11 ANSI/ISO C 57, main() ;, main(),,, : [ISO, , Sec. G.5.1]; [H&S, Sec p. 416]; [CT&P, Sec pp ] main() envp ( ) getenv(), environ ( ) : [ISO, Sec. G.5.1]; [H&S, Sec pp ] main() void, exit() return, / main(), ; main(), ( ) ( ; 11.12), void main(), void main() BC++4.5 void main() ( DEC C V4.1 gcc) void main() C void main() void main(), main(), exit(status) status main(), main() return ; 16.4, main(),

78 11 ANSI/ISO C 58 : [K&R2, Sec. 7.6 pp ]; [ISO, Sec ] ANSI #, #define Str(x) #x #define Xstr(x) Str(x) #define OP plus char *opname = Xstr(OP); opname plus OP ## ( ) : [ISO, Sec , Sec ] warning: macro replacement within a string literal ANSI / #define TRACE(var, fmt) printf("trace: var = fmt\n", var) TRACE(i, %d); printf("trace: i = %d\n", i);, K&R C, # (ANSI ): #define TRACE(var, fmt) \ printf("trace: " #var " = " #fmt "\n", var) : [H&S, Sec p. 51] #ifdef ANSI C, #if, #ifdef #ifndef " C,, /* */ : [ISO, Sec , Sec. 6.1]; [H&S, Sec. 3.2 p. 40]

79 11 ANSI/ISO C #pragma, #pragam, ( ) : ( lint /* NOTREACHED */ ), : [ISO, Sec ]; [H&S, Sec. 3.7 p. 61] #pragma once ; 10.5 #ifndef, a[3] = "abc";, ANSI C ( ANSI ) 3, a, b c, \0 C strcpy, printf %s,, abc, 4 : [ISO, Sec ]; [H&S, Sec p. 98] void*, char *, 4.3 : [ISO, Sec , Sec ]; [H&S, Sec p. 204] memcpy() memmove(), memmove() memcpy(),, memmove() : [K&R2, Sec. B3 p. 250]; [ISO, Sec , Sec ]; [Rationale, Sec ]; [H&S, Sec pp ]; [PCS, Sec. 11 pp ] malloc(0) 0 ANSI/ISO ; : [ISO, Sec ]; [PCS, Sec p. 386]

80 11 ANSI/ISO C ANSI ANSI/ISO C ANSI 6, C99 31 : [ISO, Sec , Sec ]; [Rationale, Sec ]; [C9X, Sec ]; [H&S, Sec. 2.5 pp. 22-3] ANSI, 1.11, 10.8, ASNI/ISO ANSI ANSI, ANSI,, gcc 11.28, C ANSI C, protoize unprotoize C ANSI C FSF GNU C ; 18.3 GNU GhostScript ansi2knr ANSI C, ANSI C K&R C ; , lint comp. sources.misc CPROTO cextract ; ANSI Frobozz Magic C ANSI, gcc, gcc ;, 11.35

81 11 ANSI/ISO C (implementation-defin-ed) (unspecified) (undefined) : ;, ( ),, ; 3.2,,, (locale-specific) : [ISO, Sec. 3.10, Sec. 3.16, Sec. 3.17]; [Rationale, Sec. 1.6] 11.33,, :, : [ISO, Sec.]; [Rationale, Sec. 1.7] 11.34, ANSI, C,,,,,, : [Rationale, Sec. 1.1]

82 11 ANSI/ISO C i = i++, ANSI,,,, 7.4, 11.31,

83 char c; while((c = getchar())!= EOF)..., getchar int getchar(), EOF getchar char, EOF, EOF ( char ), : [K&R1, Sec. 1.5 p. 14]; [K&R2, Sec p. 16]; [ISO, Sec , Sec , Sec ]; [H&S, Sec p. 116, Sec. 15.1, Sec. 15.6]; [CT&P, Sec. 5.1 p. 70]; [PCS, Sec. 11 p. 157] 12.2 EOF, EOF, C EOF,, Control-D Control-Z 12.3 while(!feof(infp)) { fgets(buf, MAXLINE, infp); fputs(buf, outfp); } C,, C I/O Pascal,, fgets() NULL,, feof() : [K&R2, Sec. 7.6 p. 164]; [ISO, Sec , Sec , Sec ]; [H&S, Sec p. 382] 12.4, fflush(stdout), 63

84 12 64 \n fflush, stdout : [ISO, Sec ] printf % \%, : %% \%, \, printf : [K&R1, Sec. 7.3 p. 147]; [K&R2, Sec. 7.2 p. 154]; [ISO, Sec ] 12.7 printf %lf, scanf() %lf, printf() %f printf %f, printf,, printf() printf() %Lf, : [K&R1, Sec. 7.3 pp , Sec. 7.4 pp ]; [K&R2, Sec. 7.2 pp , Sec. 7.4 pp ]; [ISO, Sec , Sec ]; [H&S, Sec pp , Sec pp ]; [CT&P, Sec. A.1 pp ] 12.8 size t, long, printf, printf,, printf("%lu", (unsigned long)sizeof(thetype)); 12.9 printf, %8d printf("%*d", width, x) 12.14

85 12 65 : [K&R1, Sec. 7.3]; [K&R2, Sec. 7.2]; [ISO, Sec ]; [H&S, Sec ]; [CT&P, Sec. A.1] <locale.h>, printf() locale : [ISO, Sec. 7.4]; [H&S, Sec pp ] scanf("%d", i) scanf() scanf("%d", &i) char s[30]; scanf("%s", s); & ; & scanf(), &, &, double d; scanf("%f", &d); 12.7 printf(), scanf() %lf, %f scanf() : scanf() ANSI, scanf %d\n scanf,, \n scanf, : [K&R2, Sec. B1.3 pp ]; [ISO, Sec ]; [H&S, Sec pp ]

86 scanf %d, gets(), gets() scanf %d, gets(), scanf() gets(), ; scanf scanf(), : [ISO, Sec ]; [H&S, Sec pp ] 12.17, scanf(), scanf(),,, scanf(): scanf() scanf %d %f x, scanf() x : [ISO, Sec ]; [H&S, Sec pp ] scanf() scanf() 12.15, , %s gets() ( 12.20), scanf(),, scan formatted,,,, scanf() ; fgets(), sscanf() strtol(), strtok() atoi() ; 13.4 scanf,, %s, : [K&R2, Sec. 7.4 p. 159] sprintf sprintf() sprintf(), %s, strlen(), %d

87 12 67 ((sizeof(int) * CHAR_BIT + 2) / 3 + 1) /* +1 for - */ CHAR BIT <limits.h>, ;, sprintf,, fprintf(), fprintf, 19.14,, sprintf(),, %.Ns %s, %.*s, 12.9, sprintf(), snprintf() snprintf(buf, bufsize, "You typed \"%s\"", answer); snprintf() stdio, GNU 4.4bsd C99, C99 snprintf() sprintf() C99 snprintf(), 0 nch = snprintf(null, 0, fmtstring, /* */ ); ( ) asprintf(), bsd GNU C, malloc, : char *buf; asprintf(&buf, "%d = %s", 42, "forty-two"); /*, buf malloc */ : [C9X, Sec ] gets() fgets(), gets(), fgets() gets(),,, 7.1 fgets() gets() : [Rationale, Sec ]; [H&S, Sec p. 356] printf() errno ENOTTY stdout, stdio, stdout

88 12 68, errno ENOTTY, errno errno 0 : [ISO, Sec , Sec ]; [CT&P, Sec. 5.4 p. 73]; [PCS, Sec. 14 p. 254] fgetops/fsetops ftell/fseek fgetops() fsetops() ftell() fseek() ( ),, 20 (2 31 1) fgetpos() fsetpos() fpos t,, fgetpos() fsetpos fgetpos() gsetpos() 1.2 : [K&R2, Sec. B1.6 p. 248]; [ISO, Sec , Secs , ]; [H&S, Sec p. 252] 12.23, fflush(stdin) fflush() flush, fflush : [ISO, Sec ]; [H&S, Sec. 15.2] fflush(), scanf() ( ), scanf(), while((c = getchar())!= \n && c!= EOF) /* */ ; curses flushinp(),,, ( ), ; : [ISO, Sec ]; [H&S, Sec. 15.2] fopen()

89 r+,,, fseek,, + fseek fflush,,, : [ISO, Sec ] stdin stdout freopen(), freopen(), stdout ( stdin), freopen() ( ), ( ), freopen(), dup(), dup2() FILE, 12.29, printf, : #include <stdio.h> #include <stdarg.h> void f2printf(file *fp1, FILE *fp2, char *fmt,...) { va_list argp; va_start(argp, fmt); vfprintf(fp1, fmt, argp); va_end(argp); va_start(argp, fmt); vfprintf(fp2, fmt, argp); va_end(argp); } f2printf() fprintf(), 15.5

90 x0a 0x0d, 0x1a, EOF rb fopen(),,, wb / :, I/O : [ISO, Sec ]; [H&S, Sec p. 348]

91 ( atoi ) itoa() sprintf() sprintf(), ; 7.6 ; sprintf() ( %ld %f) : [K&R1, Sec. 3.6 p. 60]; [K&R2, Sec. 3.6 p. 64] 13.2 strncpy() \0 strncpy(), \0 strncpy \0, strncpy(), \0 strncat strncpy : (, *dest = \0 ), strncat() strncpy() sprintf(dest, "%.*s", n, source) ( ), memcpy() strncpy() 13.3 toupper() toupper() tolower() toupper() tolower(), ANSI/ISO C, : [ISO, Sec ]; [H&S, Sec pp ]; [PCS, p. 182] 71

92 main() argc argv strtok(),,, : [K&R2, Sec. B3 p. 250]; [ISO, Sec ]; [H&S, Sec pp ]; [PCS, p. 178] 13.5 Unix ed grep,,,, <regex.h> <regexp.h> regcmp/regex, regcomp/regexec, re comp/re exec regexp ftp://ftp.cs.toronto.edu/pub/regexp.shar.z Henry Spencer regexp, GNU rx ( globbing ) Unix, shell,, MS-DOS, argv ( MS-DOS VMS) strcmp(), qsort(), qsort,, strcmp(), strcmp() : /* */ int pstrcmp(const void *p1, const void *p2) { return strcmp(*(char * const *)p1, *(char * const *)p2); } const void *, ( ),, strcmp() char* qsort [K&R2] , : [ISO, Sec ]; [H&S, Sec p. 419]

93 qsort(), qsort(), (const void*), 13.6 : int mystructcmp(const void *p1, const void *p2) { const struct mystruct *sp1 = p1; const struct mystruct *sp2 = p2; /* sp1->whatever sp2->... */ mystruct sp1 = p1 sp2 = p2 ; p1 p2 void,,, 13.6, sp1 = *(struct mystruct * const *)p1,,, 4.5 : [ISO, Sec ]; [H&S, Sec p. 419] 13.8,, ( ),,, qsort(), : [Knuth, Sec pp , Sec pp ]; [Sedgewick, Sec. 8 pp , Sec. 12 pp ] 13.9, [Knuth],,,, : : [Knuth, Sec. 5.4 pp ]; [Sedgewick, Sec. 13 pp ] C time(), ctime(), localtime() / strftime() :

94 13 74 #include <stdio.h> #include <time.h> int main() { time_t now; time(&now); printf("it s %s", ctime(&now)); return 0; } strftime(), : [K&R2, Sec. B10 pp ]; [ISO, Sec. 7.12]; [H&S, Sec. 18] localtime() time t struct tm, ctime() time t, struct tm time t ANSI C mktime(), struct tm time t time t, strptime(), strftime() partime() ( RCS ) getdate() (, C ) : [K&R2, Sec. B10 p. 256]; [ISO, Sec ]; [H&S, Sec pp ] N ANSI/ISO C mktime() difftime() mktime(), struct tm, tm mday, mktime(), time t mktime() time t, difftime() time t, time t time t, ; time t Unix Posix tm mday int, 32,736,, 24, Julian, Julian : Snippets ( 18.16); Simtel/Oakland ( JULCAL10.ZIP, 18.18) Date conversions [Burki]

95 , : [K&R2, Sec. B10 p. 256]; [ISO, Secs , ]; [H&S, Secs. 18.4,18.5 pp ]; [Burki] C : rand(),, ; sci.math.num-analysis FAQ : r250, RANLIB FSULTRA ( 18.18), Marsaglia, Matumoto Nishimura Mersenne Twister, Don Knuth : [K&R2, Sec. 2.7 p. 46, Sec p. 168]; [ISO, Sec ]; [H&S, Sec p. 393]; [PCS, Sec. 11 p. 172]; [Knuth, Vol. 2 Chap. 3 pp ]; [P&M] rand() % N /* */ 0 N 1,, : (int)((double)rand() / ((double)rand_max + 1) * N), : rand() / (RAND_MAX / N + 1) RAND MAX, N RAND MAX RAND MAX ANSI #define <stdlib.h>, RAND MAX, C rand() RAND MAX, rand() 0 1, 0 N 1, N : [K&R2, Sec p. 168]; [PCS, PCS Sec. 11 p. 172] 13.15, rand() srand(),, :

96 13 76 #include <stdlib.h> #include <time.h> srand((unsigned int)time((time_t *)NULL));,, time() time t,, : 19.36, srand() ; rand() srand() : [K&R2, Sec p. 168]; [ISO, Sec ]; [H&S, Sec p. 393] /, rand() % 2, 0, 1, 0, 1, 0,, ; : [Knuth, Sec pp ] Marsaglia Knuth : #include <stdlib.h> #include <math.h> double gaussrand() { static double V1, V2, S; static int phase = 0; double X; if(phase == 0) { do { double U1 = (double)rand() / RAND_MAX; double U2 = (double)rand() / RAND_MAX; V1 = 2 * U1-1; V2 = 2 * U2-1; S = V1 * V1 + V2 * V2; } while(s >= 1 S == 0); X = V1 * sqrt(-2 * log(s) / S); } else X = V2 * sqrt(-2 * log(s) / S);

97 13 77 phase = 1 - phase; return X; }, : [Knuth, Sec p. 117]; [Marsaglia&Bray]; [Press et al., Sec. 7.2 pp ] 13.18, #inlude,,,, #include 10.10, 11.29, 13.19, ,, ( ) ;,, Unix, -l end Unix, end,, end printf, C printf(), printf()

98 13 78

99 float 3.1, printf , 0.1, ,,,. /, printf , #include <math.h>, double atof(), <stdlib.h> 14.3 : [CT&P, Sec. 4.5 pp. 65-6] 14.3, #include <math.h>, undefined: sin ( sin ) (math library), Unix Linux, bug, -lm 13.18, , 14.2.,,,,, ;

100 14 80 C, (CPU) ( 11.34),, : [K&P, Sec. 6 pp ]; [Knuth, Volume 2 chapter 4]; [Goldberg] 14.5, double a, b;... if (a == b) /* */ #include <math.h> if (fabs(a - b) <= epsilon * fabs(a)) epsilon a 0 : [Knuth, Sec pp ] 14.6 (int)(x + 0.5) (int)(x < 0? x : x + 0.5) 14.7 C C pow(), <math.h>, 14.8 <math.h> M PI, π π,, 4*atan(1.0) acos(-1.0) : [PCS, Sec. 13 p. 237]

101 IEEE NaN IEEE, <math.h>, <ieee.h> <nan.h>, isnan() NaN #define isnan(x) ((x)!= (x)) IEEE C99 isnan(), fpclassify(), sprintf(),, NaN Inf : [C9X, Sec ] C, C99 2.8, : [C9X, Sec , Sec. 7.8] (FFT) ( ) Ajay Shah URL ftp://ftp.math.psu.edu/pub/faq/numcomp-free-c 18.8, , Turbo C, floating point formats not linked ( ), Turbo C ( Richie PDP-11 ), printf() scanf(), %e %f %g, Borland, ( sqrt(), ) comp.os.msdos.programmer FAQ

102 14 82

103 printf(), #include <stdio.h> printf(),,,,... : [ISO, Sec , Sec ]; [Rationale, Sec , Sec ]; [H&S, Sec pp , Sec. 9.6 pp ] 15.2 %f printf(), float double : char short int int, float double,, 11.4 printf %f double, %c int, %hd 12.7, : [ISO, Sec ]; [H&S, Sec p. 177, Sec. 9.4 pp ] 15.3 n long int, printf("%d", n); ANSI, 1 5.2, 11.4, <stdarg.h> 1 : ( gcc),, (printf, scanf... ), gcc -Wall, : warning: int format, long int arg (arg 2) 83