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函数大全(c开头)

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函数大全(c开头) ) ^1 v8 |' M5 s

函数名: cabs 5 J, d8 P: M+ e' r6 X1 A 功能: 计算复数的绝对值 + O- `% J6 Q" a: q! F* Z- j; k用法: double cabs(struct complex z); 4 I l* k6 e8 W2 ` o2 f; Y程序例:

#include 9 I8 v6 W! x+ J# m, W, G; ?! @% K! Z#include

int main(void) 5 T0 p- _* F+ t7 U{ " w: {4 y, s5 B- B! S* K, ~struct complex z; - [9 D3 i/ k$ r+ P( C( L f8 F# F7 idouble val;

z.x = 2.0; ; O4 N3 Q2 p; I( J: S z.y = 1.0; 0 [; P' H6 R6 Z8 S9 v6 n7 Kval = cabs(z);

printf("The absolute value of %.2lfi %.2lfj is %.2lf", z.x, z.y, val); $ p8 \& W$ h* T# t return 0; 7 \8 D" y, \ M5 d8 G' q/ R$ ^} F. C, G' Z4 B( Z ) s1 Y$ I6 q$ U ! f; v& [* x' w3 s, a! M

函数名: calloc 8 n* M$ K# x: t4 g) H8 s功能: 分配主存储器 4 R5 S2 ~7 t8 r' h! h# _用法: void *calloc(size_t nelem, size_t elsize); 0 K! y" k1 b$ R" }5 j) S3 g程序例:

#include # L, ?' p% e n+ Z2 C #include

int main(void) 6 D( A3 Q c4 }, M7 n{ ; n3 d; ~! H5 G1 qchar *str = NULL;

/* allocate memory for string */ & M' \- D4 U5 c str = calloc(10, sizeof(char));

/* copy "Hello" into string */ 3 i: c$ M5 {5 [7 ]9 K% @- t! k strcpy(str, "Hello");

/* display string */ & o% w9 W$ V0 Z/ l) yprintf("String is %s\n", str);

/* free memory */ 2 O; p1 ?7 M! p4 ~free(str);

return 0; * `8 A+ v% k$ [) \ } ( P9 j% U* A2 P9 d : w' Z% }5 e' a: k' `% a( V/ l$ G. I8 L6 p+ r

函数名: ceil * w' i( ~) K4 D, S$ r* | D) q功能: 向上舍入 1 g8 {- s0 s" W' _1 Y! W4 f* d用法: double ceil(double x); ) s$ f5 J+ l% C) L$ r2 r8 M程序例:

#include 4 |4 ?7 g, \ i5 o& b6 e* k #include

int main(void) - r8 [/ H5 G& `, c+ B9 ]0 Y* u" g { ! T. c s, X: C9 h8 R0 z! |double number = 123.54; . e! [( ?5 X6 G6 V5 P h& m double down, up;

down = floor(number); % J/ E9 G+ B3 m: y up = ceil(number);

printf("original number %5.2lf\n", number); : M4 c0 \$ S3 W# x' b/ jprintf("number rounded down %5.2lf\n", down); & D, k1 G' c5 d printf("number rounded up %5.2lf\n", up);

return 0; : H- O. D$ O4 ] } 0 |# ^ [. @% \! ], d " x. y! |. J$ V: B; Y) G" G4 y- B( z$ t. v9 {) y

函数名: cgets $ c7 d; i5 Q ]% [& y# \1 t功能: 从控制台读字符串 3 N0 s/ ]' {- |7 \/ V/ ]用法: char *cgets(char *str); - o4 E% h$ x: W. X程序例:

#include k T3 T& \- M$ r3 l4 h" H1 M#include

int main(void) ! j0 c+ f6 |/ a6 Y$ z{ 4 a# J8 y6 u7 h! J/ O char buffer[83]; : a+ c+ H' g# Y' [char *p;

/* There's space for 80 characters plus the NULL terminator */ - h" ~* i) ^" m6 r4 G( _! n# _ buffer[0] = 81;

printf("Input some chars:"); $ Y9 ?' w. p2 s6 d p = cgets(buffer); ; G& k& C* o4 f- c1 J( wprintf("\ncgets read %d characters: \"%s\"\n", buffer[1], p); ) P, d4 F2 S- U# ^ printf("The returned pointer is %p, buffer[0] is at %p\n", p, &buffer);

/* Leave room for 5 characters plus the NULL terminator */ 4 `9 R1 I! y2 L4 W$ hbuffer[0] = 6;

printf("Input some chars:"); : u2 w3 S# j# L, p" ~* A R p = cgets(buffer); 6 {" a( Z8 S4 |3 e4 M printf("\ncgets read %d characters: \"%s\"\n", buffer[1], p); 9 \" B0 G; j c4 I0 gprintf("The returned pointer is %p, buffer[0] is at %p\n", p, &buffer); 6 f4 ~( M0 F8 r+ n- x0 M return 0; 8 J% Y* c r/ F/ C0 m} $ I) L6 _& \1 Y% T; ]2 B; i* d* z( H- h. L 0 F; M0 c/ ?. f+ V, w

函数名: chdir B. Y0 X3 z3 [% d1 j功能: 改变工作目录 & g- R3 H4 p7 T* [9 e 用法: int chdir(const char *path); 3 l9 m% I0 M7 U* ?8 J程序例:

#include % S6 x, t) P3 C# l3 I7 h #include : O- Y2 j) y# l/ n6 Z. M #include

char old_dir[MAXDIR]; ; o1 _! I! W5 q* j char new_dir[MAXDIR];

int main(void) 0 `8 M0 k- u) e& s" T { % x1 `* n9 Q) o2 mif (getcurdir(0, old_dir)) 8 ?+ w8 i# A9 y. d1 } { ) d+ e9 ^8 Y/ `; R) b; N- D# cperror("getcurdir()"); $ @/ M( W7 m4 q( w+ bexit(1); * H# J" S( W! \3 c2 e} - |, A1 \3 R" Z2 J5 y printf("Current directory is: \\%s\n", old_dir);

if (chdir("\\")) ( z" b, B' U# D, F { " T q2 R3 Q/ ] | perror("chdir()"); # {. N ?, W! p' W% mexit(1); & u* ]+ l, X2 u q3 C3 L" f}

if (getcurdir(0, new_dir)) 2 g; { g7 `( G m6 y{ , @8 D$ ?6 [+ s/ e3 S0 l- w1 T perror("getcurdir()"); / K2 q/ {0 e- E exit(1); . t( D2 L' Z% R; o `% H} * I; O8 V$ R- g" s n; dprintf("Current directory is now: \\%s\n", new_dir);

printf("\nChanging back to orignal directory: \\%s\n", old_dir); 9 |, \( d* `4 h0 S% j' zif (chdir(old_dir)) * U0 G: c6 O8 \6 u{ - ~1 W8 x0 K( @: B1 ]: \ perror("chdir()"); 9 c3 @. `; e/ X& p" d9 x0 r8 l/ s8 ^" w( R exit(1); - A5 p/ i/ g4 l }

return 0; 4 g) s4 g' t" [- Q) B2 Y; h+ H} 5 X! c* z) @2 x2 z4 ` 9 G8 z7 i0 V: P q1 }8 X+ \) {

函数名: _chmod, chmod # o/ ?: g* Q. z: c) A: c) e) B/ b- u功能: 改变文件的访问方式 ) R9 V* k9 v" W9 _, H0 n用法: int chmod(const char *filename, int permiss); / V2 `3 c* \- ^3 D% K* g 程序例:

#include 7 C" e8 R3 Z. h, h# _; K #include 3 {# O: `# K/ o) u# D( c #include

void make_read_only(char *filename);

int main(void) 6 w8 u4 c W2 @" F{ . o6 Y, Z# I. p" Y$ r6 H make_read_only("NOTEXIST.FIL"); - E G. M7 z0 O4 T7 Umake_read_only("MYFILE.FIL"); # G. ^/ d5 J5 X- r2 _1 | return 0; 0 M0 X, [6 T* j$ ]}

void make_read_only(char *filename) 9 w& V0 B7 N$ N) A9 R{ ! \0 D% V; ^$ dint stat;

stat = chmod(filename, S_IREAD); - ^" a2 l: `7 u( ~' K if (stat) , x. U$ ~- K# ]$ t* F N5 G6 zprintf("Couldn't make %s read-only\n", filename); 5 c( F: A4 ?7 C9 C else ; v$ S$ v$ B% z5 w; W ` printf("Made %s read-only\n", filename); . w2 u& k- n8 x4 w( [1 V} 4 b6 W5 K! _ l7 g/ u, w i0 H1 |8 z$ P4 w. T 4 Q" Q; \. s4 m" z) N8 e

函数名: chsize 5 f4 O; I. v) h6 b m% Z/ e 功能: 改变文件大小 - P5 S2 K" W+ Y: o! n! b用法: int chsize(int handle, long size); - \! A+ h: P( ^6 r 程序例:

#include ' p' v# G: y5 A, e! b9 k#include % d) b4 L; u# U' R! o2 ]' Z, v$ _#include

int main(void) / g' `. t; u9 M# k( [. w& m{ T+ t2 @$ o; V9 T int handle; / c! ]3 r1 a0 V3 m l! f! a1 Y char buf[11] = "0123456789";

/* create text file containing 10 bytes */ 1 o' N/ s' Z! p6 e3 D( ~. W) |. } handle = open("DUMMY.FIL", O_CREAT); # I4 S# f( \) H- k* B% Q write(handle, buf, strlen(buf));

/* truncate the file to 5 bytes in size */ 8 r+ z- L0 x9 B, Cchsize(handle, 5);

/* close the file */ # `1 L% G* _2 b! T" `6 |+ S. {3 Jclose(handle); 1 Q9 y1 f8 R5 E7 h0 Y7 e1 ]& w return 0; 6 G! y2 F6 N e" h} 0 A4 E3 l$ M- B. v1 I% b + I8 d3 c; ?% A' n% }8 F& n1 O

函数名: circle $ a9 h1 W: K9 f& G8 v, g" F: o 功能: 在给定半径以(x, y)为圆心画圆 5 P$ Q8 c" E7 K Z |" U: d用法: void far circle(int x, int y, int radius); ( H0 y9 @9 T* d: [* r 程序例:

#include : _5 `1 O8 T% G #include 8 C7 |' N5 W* L% O #include . f9 D" R! g( f j6 {* u O#include

int main(void) , R1 `7 I! J3 m6 [+ w- C{ " |2 \. E0 z2 I. Y6 h/* request auto detection */ # r! K- F0 r; `int gdriver = DETECT, gmode, errorcode; . P- ^& P/ r7 {" {int midx, midy; # x2 J3 V. f3 E7 r. y, l' Fint radius = 100;

/* initialize graphics and local variables */ 4 |( v: F- ?- k& M O l initgraph(&gdriver, &gmode, "");

/* read result of initialization */ % U/ m. n4 j7 a! r" u! o# t errorcode = graphresult(); & ~. j& H, l7 v( C: z- i+ P if (errorcode != grOk) /* an error occurred */ # u& K( A) z. m { : N3 p2 C+ p) M7 H0 Uprintf("Graphics error: %s\n", grapherrormsg(errorcode)); $ |# p& z$ y$ i2 b( _2 X/ @ printf("Press any key to halt:"); 1 U! \8 j& W4 o/ ]/ i; y" } getch(); & n* z# ]# a) \2 M& w7 ?# @( A exit(1); /* terminate with an error code */ ' a, h( ^6 r! P+ B3 n }

midx = getmaxx() / 2; 1 s' R4 i% ^. I/ E9 c \/ ]midy = getmaxy() / 2; 2 \3 H9 T4 p. E6 k0 I& k4 ^ setcolor(getmaxcolor());

/* draw the circle */ * y {0 v8 y+ v: w circle(midx, midy, radius);

/* clean up */ : }& G* |& D' z/ {( J' q9 z getch(); - }, p+ n& S! g, {* E2 N3 C, Cclosegraph(); 2 }5 Q# O2 k7 h return 0; 5 |4 o% f& {8 D: f1 l) M" H# N } / v9 {. x) N: ] B1 u ' Q, G9 [" S9 O1 ` ! a3 F( G; b6 ]9 w

函数名: cleardevice ! a0 k9 X9 d) S; f5 w( g功能: 清除图形屏幕 9 b- j8 e* ^* Z+ D用法: void far cleardevice(void); {, m# u! S5 r* ` r H% u- { 程序例:

#include 4 H: B; W* A5 L8 O #include " x& x. [8 [; F- P: r' ` #include 7 T1 ~) U9 j/ E #include

int main(void) 7 G' g% P% |3 k9 F+ O0 t2 p0 q { + Z- p9 R1 T' C! D /* request auto detection */ . |9 Z; C: z" S3 x4 f! pint gdriver = DETECT, gmode, errorcode; / V1 }* X4 \6 A6 Q( U$ Dint midx, midy;

/* initialize graphics and local variables */ ( b. i. p3 j" X- v) ?+ einitgraph(&gdriver, &gmode, "");

/* read result of initialization */ % }' k2 O3 |) l+ H( ^; ` errorcode = graphresult(); 5 n' j) e' D; |: ^ qif (errorcode != grOk) /* an error occurred */ , r; \8 Q8 T; H$ M+ j F9 M' _; {{ ) L6 t. s: W5 h7 F3 J' Z printf("Graphics error: %s\n", grapherrormsg(errorcode)); 7 ?8 v" j0 B" P% U' v/ H6 ~6 l' q printf("Press any key to halt:"); ( m3 Q6 S' m o3 r' O! p/ N% {getch(); 9 E, e# Q; g( b% R( Q. c7 Aexit(1); /* terminate with an error code */ 5 I+ Y5 R0 q" E# ?}

midx = getmaxx() / 2; 5 a& J" E8 |( d$ |3 [ midy = getmaxy() / 2; : j# U. W3 `, p0 L( Ksetcolor(getmaxcolor());

/* for centering screen messages */ + e7 k) c9 {" H6 E2 u+ V" osettextjustify(CENTER_TEXT, CENTER_TEXT);

/* output a message to the screen */ % ?- V; f* q2 ]* X# M4 m outtextxy(midx, midy, "press any key to clear the screen:");

/* wait for a key */ 1 L6 H6 ~& Z' F getch();

/* clear the screen */ 7 D4 W6 z' P- S! `cleardevice();

/* output another message */ 5 c: Q/ M3 d8 U+ g! Uouttextxy(midx, midy, "press any key to quit:");

/* clean up */ ; u, y' w e8 N1 r: X getch(); $ ^9 O, X, ^2 Kclosegraph(); / [ t3 L2 p5 v% s t return 0; 3 V' K' r2 P1 g/ J5 ^; [0 q7 q} ' r" y' v, w2 _) ^+ W% ^ ( Q2 w4 ]+ H5 T0 ]: A# m 1 e9 H; t+ k' i+ A& i0 C

函数名: clearerr " `2 ]4 z3 ^) c2 M 功能: 复位错误标志 9 L/ \9 f5 ^5 A6 e9 U3 W 用法:void clearerr(FILE *stream); % d+ H4 a& y$ e$ o程序例:

#include

int main(void) , B& e- h# K, E0 N7 D) h& D& [5 ?{ J6 W% U2 ]0 S/ h5 D FILE *fp; $ z& Z9 K; H% h }8 |char ch;

/* open a file for writing */ + n9 Q7 G. i- h$ C) H, V. h fp = fopen("DUMMY.FIL", "w");

/* force an error condition by attempting to read */ , j7 m* Q9 g1 J* d5 Nch = fgetc(fp); % ^. U* C- ^; A# W/ F printf("%c\n",ch);

if (ferror(fp)) ' N# h6 F- X6 s O w9 |{ $ \+ D, s9 w% R /* display an error message */ ! Z" h% y' w" V" w7 Z) f5 V1 A/ i e" Tprintf("Error reading from DUMMY.FIL\n");

/* reset the error and EOF indicators */ & V, N' c N- D: q* u; I clearerr(fp); 6 U7 M2 b1 V& V: O6 h# [1 \# O }

fclose(fp); & T4 e/ w; A) C6 P, k( E return 0; / J1 \$ [( o9 P7 A* @3 \' g} 9 j6 V* l6 A" z" J - N$ o" K' p9 [1 U0 R 8 Y9 h5 ]0 z! O' H" X

函数名: clearviewport 1 m$ K2 f: P, n& b& U5 e4 Z功能: 清除图形视区 9 K4 ]% B& t0 K; O% r( n3 S- n( N 用法: void far clearviewport(void); 3 m! _6 [/ H& X; O" p; }+ X 程序例:

#include ! a7 Q/ H' x* b8 L#include % t0 ~+ H6 Q- Y" n1 n0 \& T. t. q% K #include # {2 O( z5 k. r+ x" l#include

#define CLIP_ON 1 /* activates clipping in viewport */

int main(void) / v. J# j% l( L. ^ { : W4 C1 k8 J4 G3 _: V( \/* request auto detection */ - i; B5 d9 `3 o3 Q$ ~9 m, Uint gdriver = DETECT, gmode, errorcode; ; b. Z- E5 @- rint ht;

/* initialize graphics and local variables */ ; J7 I" w$ s/ p1 _$ P6 _ initgraph(&gdriver, &gmode, "");

/* read result of initialization */ & j4 [ }) n7 D! v v$ P. E1 \/ y; Q errorcode = graphresult(); 4 ^7 q9 p/ P! J# j; H" J3 T$ rif (errorcode != grOk) /* an error occurred */ / p9 C1 {" d) d8 B! l' k: i5 f$ J. w{ + r* k8 E3 D5 ?7 Q4 s; [ printf("Graphics error: %s\n", grapherrormsg(errorcode)); x j$ A. b2 Z6 |printf("Press any key to halt:"); y& O: E3 d! y9 Tgetch(); $ j& z+ ~; T' L5 N6 v/ e8 jexit(1); /* terminate with an error code */ 6 f1 h/ |) ]8 g; X}

setcolor(getmaxcolor()); . ?: ]% f3 M8 Z' `. N! c' |8 ~- k/ G/ iht = textheight("W");

/* message in default full-screen viewport */ , W; Y4 G$ @& L outtextxy(0, 0, "* <-- (0, 0) in default viewport");

/* create a smaller viewport */ $ i7 b- G0 C$ _7 ?. b/ d5 b! N- \% z setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON);

/* display some messages */ : f. @. {1 g" P9 l. n0 C ` outtextxy(0, 0, "* <-- (0, 0) in smaller viewport"); 1 T- F _) I9 }$ {outtextxy(0, 2*ht, "Press any key to clear viewport:");

/* wait for a key */ E" K0 U1 R' \1 L7 G& a getch();

/* clear the viewport */ 1 L# ~. F! N/ S1 ` clearviewport();

/* output another message */ 5 {/ E; d* I: { outtextxy(0, 0, "Press any key to quit:");

/* clean up */ 7 s. z# R7 |9 d4 P; E0 B- B) Q getch(); # ]+ t# ^0 ?8 t0 q# X closegraph(); * ?9 C' f* E* h& A7 Z return 0; : j9 J3 O, q, z} $ L; {( o/ h0 q3 Q7 e# [) { * D3 J- o' U/ L/ X1 u# p2 n# k* M4 i% W" ?6 k0 E4 N

函数名: _close, close ( t" d& S }/ Q6 T0 ?# W' ?功能: 关闭文件句柄 $ L3 W' i3 o' b; {) X6 o 用法: int close(int handle); % S, g/ n1 H# W" O程序例:

#include 6 \: s! n1 l5 D& P' @1 ?#include ; S" i7 r' \% d7 G/ H #include " w& f/ N: O H: S#include

main() 8 w" |% P1 L! r' s { 2 } G( T/ @' b& u+ q$ iint handle; $ ] r9 W; h$ {( t4 z char buf[11] = "0123456789";

/* create a file containing 10 bytes */ 0 w0 f: N4 r2 B# a2 \& x handle = open("NEW.FIL", O_CREAT); 2 c7 d& r% n _+ u8 a% _if (handle > -1) , C5 U" ~% Q; t# b( d- R$ }{ + f# q! B$ e# B write(handle, buf, strlen(buf));

/* close the file */ 3 K, y: V; x* |4 _ close(handle); * K7 Y, n; b1 m8 ~} ) {9 j& ?) d4 X0 `1 c v9 velse - i5 T& ~0 E, Y5 q) P- e( r { ; G9 M( ~8 D# H printf("Error opening file\n"); , C4 [: p" v3 U- g } % W$ x: D5 t$ R; q& j) ] return 0; ( h% x+ h2 n2 o) I ~$ o& { } . I% m3 G8 W4 C, _7 t ) F7 m( a& W$ G! g' {( z; { 4 s( @* X+ B* J

函数名: clock # G4 T, A) `* b7 Y- I! S* [$ L功能: 确定处理器时间 ( c& _6 p" k* Q+ F: k! ?% \用法: clock_t clock(void); 2 E9 @3 ?4 a$ K; z程序例:

#include 4 r3 Y) }5 D6 i3 @3 l8 O1 D #include 2 E9 p2 }! q+ f. m8 B- G#include

int main(void) ) N# [+ {$ R9 S! C" p" a { & |, J4 F4 R1 `( x) Z7 U9 \clock_t start, end; 7 ]1 K! e. A" P8 }$ Q- a) M/ z# F start = clock();

delay(2000);

end = clock(); / R- J3 V6 ^8 r3 y printf("The time was: %f\n", (end - start) / CLK_TCK);

return 0; + B5 u9 o: b8 B8 q- e: F" R3 ~ } 7 A- K- ] r$ i7 [3 k1 a* q& L, C ! m" R* K- E/ v% ]6 M% F: n 9 G7 M) R; K% {% z. s

函数名: closegraph ! k* F4 t$ g( z. S* d2 o 功能: 关闭图形系统 # c7 c& @ ^# a) f" y8 l用法: void far closegraph(void); 2 d8 s7 i' N, k# H0 U程序例:

#include / H9 M; q T: B! B2 Z/ g- Q7 S #include / @+ I% W ]) v# X" W #include * [8 Z5 [3 C4 a% |) T #include

int main(void) / b2 R& W: K- [! Z+ x { ! Q7 U6 e8 K) N6 y9 v" m/* request auto detection */ ' l7 Y" W1 U+ c: r: Q+ r+ lint gdriver = DETECT, gmode, errorcode; 6 G! ^0 j- c! v5 ?3 a' N! Y3 f int x, y;

/* initialize graphics mode */ 9 X& F, M* t3 E1 ^! d n5 W6 s# y initgraph(&gdriver, &gmode, "");

/* read result of initialization */ $ \* p" O) F0 e0 _2 U3 s* ^errorcode = graphresult();

if (errorcode != grOk) /* an error 2 ~$ Z- I! e W' X: S6 t# }/ O; o2 o occurred */ % p; {% y/ Y2 |2 o{ ( O# M S8 T9 B$ z% xprintf("Graphics error: %s\n", grapherrormsg(errorcode)); / i9 h$ ~# D9 z) `+ t6 M) [' {9 a% \" bprintf("Press any key to halt:"); / o0 z' t3 J p% U2 S, z getch(); ' x: T- o+ r) f' M$ ~9 Y0 J' s! X exit(1); /* terminate with an error code */ ) i% q( }( A+ U- L }

x = getmaxx() / 2; / K4 s: I' k6 C y = getmaxy() / 2;

/* output a message */ 0 _2 Q* j6 |% Xsettextjustify(CENTER_TEXT, CENTER_TEXT); / F u- y! r% y3 F5 a+ Fouttextxy(x, y, "Press a key to close the graphics system:");

/* wait for a key */ 4 z; W3 A/ V5 X& ggetch();

/* closes down the graphics system */ + H" N8 ~2 ?" }& q+ `2 H x closegraph();

printf("We're now back in text mode.\n"); # ]# j$ [$ z- X8 p: n, Qprintf("Press any key to halt:"); 0 P: c9 g7 v3 V; M1 ~, Sgetch(); 7 S, d0 F) q( C* L( y% B1 h, mreturn 0; 6 s% l( M! q: \8 y. ~: u } . Y3 {; k8 Z- {. V" o! ]% q y : [( P, X4 z$ r, L0 r % x* E1 Q2 ^# i7 x7 x

函数名: clreol 6 t. r! Q7 H% C" B& `功能: 在文本窗口中清除字符到行末 # |5 x( P5 W# T0 Y: I用法: void clreol(void); + Z. Q, `$ U/ k8 K. _ 程序例:

#include

int main(void)

{ 3 ?# w) R8 i7 C6 Xclrscr(); 6 U# A+ A7 b! D- O+ O cprintf("The function CLREOL clears all characters from the\r\n"); 0 j7 Q1 E9 \; t: s- {2 } cprintf("cursor position to the end of the line within the\r\n"); & W$ Y" e; X5 e6 zcprintf("current text window, without moving the cursor.\r\n"); $ H$ i5 F! h4 r- N' l cprintf("Press any key to continue . . ."); 5 u7 _; s5 S4 e8 _0 x* Z gotoxy(14, 4); $ y3 L3 h! a# r' K+ F- ~+ agetch();

clreol(); 8 Y% ^; h1 e/ F4 K) vgetch();

return 0; ( r! w3 C1 Y! X2 g; ?) m6 f+ j} 8 S( y7 G) z7 u3 F/ N- N2 K3 l9 Y7 x/ O9 @- ? * q, S- [- Z3 C1 _0 u+ s

函数名: clrscr & Q Z7 ]0 X4 G8 V7 X( `" M 功能: 清除文本模式窗口 % v+ ^+ [1 {7 G: N/ d" ` 用法: void clrscr(void); ' K# C4 O" [, a% z 程序例:

#include

int main(void) 1 h! K5 n7 I! L0 ]* z$ O { : P3 x/ T. C1 n3 ?* g0 G6 Y- R Nint i;

clrscr(); ; E" J X) a! W: Gfor (i = 0; i < 20; i++) + F3 d( N, R1 c* I, R% E1 Ncprintf("%d\r\n", i); ; W! o& B" l0 Tcprintf("\r\nPress any key to clear screen"); & F! Q% g) w+ Ggetch();

clrscr(); 6 _% K, f* W9 e0 t- v) Bcprintf("The screen has been cleared!"); $ P0 Y# S2 a8 t3 k9 tgetch();

return 0; 3 F# d- B9 ?/ W0 j5 f! T( f8 p0 a} - S' P; v. S. y1 } " }5 C) p9 w/ v6 J8 _5 p1 [: t5 @7 ]

函数名: coreleft ; C' y5 a8 h- e' s+ M. U9 o功能: 返回未使用内存的大小 ; b) [% i& {/ N( c }# n* x 用法: unsigned coreleft(void); 4 s8 I( t* \% t+ K' E1 A Z. x程序例:

#include 7 ~) `( \; H: \' D #include

int main(void) % M. Z8 A8 j# v! r7 O9 k{ % W/ y* C3 i8 F/ a; s# R6 M printf("The difference between the highest allocated block and\n"); $ i4 T8 j8 m& Q3 [7 \( sprintf("the top of the heap is: %lu bytes\n", (unsigned long) coreleft());

return 0; 7 J" p; ~. L4 }9 [4 p} ! M s0 o4 G$ P; C

函数名: cos # n% R5 x7 Q: d' }2 }6 L功能: 余弦函数 4 N6 O, Y$ o' A. W9 Y; F 用法: double cos(double x); : {2 D) y: @& \# ~6 ? F# p- U 程序例:

#include 8 t0 @9 O" T2 J #include

int main(void) 6 b1 o$ O5 H) U8 x5 T! J: O{ , U/ T/ o7 T s8 i5 d0 u double result; 1 N e7 Q: V: r. Rdouble x = 0.5;

result = cos(x); 0 ]5 Z- n. ?3 D% xprintf("The cosine of %lf is %lf\n", x, result); + f: E Y) D4 T4 V/ ]2 n% s return 0; $ o) j( S9 f5 C} 4 E" T7 a' b& K, n7 v% E0 B 4 T) t0 ^3 d: C+ }' N4 L+ e/ p+ A1 B$ N

函数名: cosh + W2 F2 l- H( {% d; Z" a. L. f功能: 双曲余弦函数 7 U k/ u) c- i 用法: dluble cosh(double x); - V2 [0 P6 U: P) w! y9 }6 K程序例:

#include - }: z; ?5 F0 O% k9 T4 i#include

int main(void) 1 L+ ^6 T1 @+ u' i- q0 ]{ , O4 o; D' ^: k* C# P+ m1 {double result; 1 M9 `: x" w/ T1 k6 `2 T double x = 0.5;

result = cosh(x); 2 M$ L' H' I4 H+ Zprintf("The hyperboic cosine of %lf is %lf\n", x, result); , E; @% `8 j7 B9 j/ Dreturn 0; 3 I& z' ~/ P9 y* q# G) v } & O. `' N. F1 e9 G4 F, S8 q& b" q4 K- R; j8 C* ]3 n 8 m* r# r4 Y1 g/ a

函数名: country , O* _* G: Y3 d o 功能: 返回与国家有关的信息 9 C4 }1 V( q' J0 m用法: struct COUNTRY *country(int countrycode, struct country *country); 5 w7 J9 H8 [" J! y+ R c: E K* O: ` 程序例:

#include b/ u [8 c) _: H& e [ #include

#define USA 0

int main(void) % m2 Q$ w/ |* S( z2 ?1 L b7 X! {( e { & Q, |8 a Y4 B' w6 [7 Zstruct COUNTRY country_info;

country(USA, &country_info); ) `2 i( z, A& Sprintf("The currency symbol for the USA is: %s\n", / B' {( y) C+ R; l0 J! D2 ]' Acountry_info.co_curr); e; g2 S6 G) |( P \return 0; : T0 |0 q+ A8 h/ y. t7 I1 ~9 `} * N/ l u C: o4 w* Z; Y 8 ~( @7 z. H& m: G0 K7 w& r3 m3 v7 F v8 D

函数名: cprintf - m: m/ [, y+ F9 O8 k功能: 送格式化输出至屏幕 ! T+ R& b4 r1 R7 [$ Q5 Q用法: int cprintf(const char *format[, argument, ...]); 6 A0 ^% ~3 j7 }; x: o3 Q: y b& x% W 程序例:

#include

int main(void) 4 |5 G$ Q; B+ m! ]' t) r{ 4 L, j' F* t) ^+ j( A/* clear the screen */ & [9 i$ r( g( w* W# t5 p' S1 c. g# p clrscr();

/* create a text window */ - ^( L- D( g- U window(10, 10, 80, 25);

/* output some text in the window */ ; S8 O; |6 v* d7 o4 Q cprintf("Hello world\r\n");

/* wait for a key */ $ E& H/ |1 i! M, y9 s. o$ a$ u getch(); 4 _: }. o* |# k- V, g; o% @( ? mreturn 0; 9 S( K8 P7 t6 A- H% V} ) x2 U9 z& ?5 L. L& N) v1 w- s# Z; T$ r5 M0 B4 s ' v; `( N* \1 u: v

函数名: cputs ! o0 ?# T$ U2 }- i/ Z功能: 写字符到屏幕 0 m4 e3 v. e) T3 y9 `8 d用法: void cputs(const char *string); & o/ z& _, F7 S* T. N" g) e4 T程序例:

#include

int main(void) ( M$ ?. h s7 R+ L& v1 b{ 6 |6 a! E# M# C, _/ `0 q" X /* clear the screen */ 3 _$ m0 X9 h) c6 H* B% X0 b" yclrscr();

/* create a text window */ 6 u& L* B/ _2 K; K& `8 K1 R* Qwindow(10, 10, 80, 25);

/* output some text in the window */ 9 d9 b. J8 {3 ?! |6 ^cputs("This is within the window\r\n");

/* wait for a key */ # }8 a3 c, Y$ y1 H3 L) ogetch(); 8 N2 X9 W) e" `$ l return 0; ?; s: C2 D( {, q } ) y" N; J5 |$ s6 M B7 h2 ?, |; ^! ^) Z0 m. H- B ! [/ }8 |2 Z3 x4 R% T, H

函数名: _creat creat ( k' }: q' E: X6 V+ q+ l 功能: 创建一个新文件或重写一个已存在的文件 ! m& D# B, c& d 用法: int creat (const char *filename, int permiss); 4 ?1 s% v1 q. C+ O程序例:

#include 5 J! z; Y( l1 H' W1 }1 D#include ) D! s& p Y& ~, `7 E#include - D# L& f: v6 x4 A- Z #include

int main(void) & g2 ]: _7 g8 T5 q3 \ { * m1 I! F, D* R w$ Mint handle; : c3 O+ K( p6 s char buf[11] = "0123456789";

/* change the default file mode from text to binary */ 5 r7 g9 l" G3 Y6 ` _fmode = O_BINARY;

/* create a binary file for reading and writing */ 6 T# F. H: r+ @8 Z5 ~8 a handle = creat("DUMMY.FIL", S_IREAD | S_IWRITE);

/* write 10 bytes to the file */ . N. [* x [4 E1 f7 m, P* p+ Nwrite(handle, buf, strlen(buf));

/* close the file */ ( r3 v/ D7 c) ^7 { o Iclose(handle); 8 b- w# f/ j& r/ l4 X! y( b/ ~ return 0; 1 k9 z1 F' d7 E" l x } # O8 y! | `( E) Q2 t

函数名: creatnew ( ~9 [: _7 z" p X9 E 功能: 创建一个新文件 1 V9 W; \5 l3 _4 ~+ J4 Y |用法: int creatnew(const char *filename, int attrib); 8 s2 c" Y: I8 g 程序例:

#include 7 K& l; |; n( |8 @" W; }, i: \: |#include ' n$ _+ s* q% A! i, u( A/ W# t#include ( M+ x7 @1 [# l0 Y#include . D' G# O9 W" G" \$ d' M#include

int main(void) , Q) `2 }) Y8 k. c' D- L8 K{ ! |6 j+ ~0 v# M9 }) [' o5 @3 E4 qint handle; 7 H! t: ^. T" x, b" l" y' B7 A char buf[11] = "0123456789";

/* attempt to create a file that doesn't already exist */ - L1 t$ t& y( @/ D* g W handle = creatnew("DUMMY.FIL", 0);

if (handle == -1) 8 |0 W/ z( X7 ~+ C# u* \ printf("DUMMY.FIL already exists.\n"); - r7 ]) D, y y) t* H else 5 Z; `7 C% R5 N5 n1 ]6 }! g { 2 g5 `! ~; S* ]& tprintf("DUMMY.FIL successfully created.\n"); ' I, w& G _" l write(handle, buf, strlen(buf)); 5 M, n% h B+ ^& ~- V% x+ J' l, o close(handle); - c+ E' \7 ?4 b, k$ J0 x6 b } * H+ r+ n9 `4 T9 W return 0; . F# X" T$ t1 D3 k# k; B" U } 9 q( m5 S+ P+ d5 \8 g8 L : f7 r/ w8 i ~( v+ X& q, X+ e6 j: z$ e( E4 \1 q$ q, H

函数名: creattemp $ m6 E; p+ v5 _* f, x 功能: 创建一个新文件或重写一个已存在的文件 {0 B( M, p7 f! o9 E9 _" z 用法: int creattemp(const char *filename, int attrib); : a, w2 U8 a/ C$ b0 }程序例:

#include 7 e0 \& q+ f4 g. |#include ( Q6 N0 ?, S3 G- c% Q #include

int main(void) # ~ ^6 y5 y5 l1 r0 k- D" { { : \3 j% Z: P% j int handle; @/ A, }: l5 o) dchar pathname[128];

strcpy(pathname, "\\");

/* create a unique file in the root directory */ 9 {. \6 g$ x, Y4 J/ z: e4 g handle = creattemp(pathname, 0);

printf("%s was the unique file created.\n", pathname); T3 T* G' S6 D* V' |# hclose(handle); 1 n! l0 k8 h5 z* |( {return 0; ! Y3 {6 ?2 r A. S2 \} / G1 M. ]5 G2 D6 L: E+ N) x9 t 6 W1 ]& R3 F6 c! } A3 U/ d. q& t

函数名: cscanf 5 j( |$ @1 L$ Y, \. n4 H; e功能: 从控制台执行格式化输入 9 {+ E" ]& J! m1 G Q用法: int cscanf(char *format[,argument, ...]); 6 X# M& G/ p0 ?( y程序例:

#include

int main(void) * v& V- k! [% X' i1 [4 q6 o# D { " E- |0 F. m0 P E8 ~ char string[80];

/* clear the screen */ - f( w1 ]3 \3 F5 t1 d8 } oclrscr();

/* Prompt the user for input */ [& q: K0 Q, h3 P0 ]' L; Gcprintf("Enter a string with no spaces:");

/* read the input */ + K& K R8 I( q6 t4 [cscanf("%s", string);

/* display what was read */ 0 {+ C2 T5 d+ c$ a8 v* B9 r2 ~cprintf("\r\nThe string entered is: %s", string); 0 e3 f6 C% f# l9 J return 0; 3 p+ H! P7 e9 {+ F" E8 l( h; W} 5 M* U! S, m' g7 p; N4 p - g/ q1 a# F6 e8 Z, Z u% ^( W. A/ T" j2 k" o+ A" q

函数名: ctime 8 \0 f. b- N0 c功能: 把日期和时间转换为字符串 / m& y. ?% E7 f( r& I& q' l 用法: char *ctime(const time_t *time); 3 V! y8 f, N8 t/ \1 x 程序例:

#include 6 H8 w1 f6 Q; g+ h #include

int main(void) : ^' c z* h M7 M { 5 } i# s7 r$ u6 G' I time_t t;

time(&t); + A) g J7 s/ B4 V printf("Today's date and time: %s\n", ctime(&t)); " I0 D d5 S# l; r$ v* |' Kreturn 0; + Y) {4 S! J2 B; X) ?' S } + ]% Q( W2 j1 u0 g7 C/ s. S' f' j6 N- l5 b0 B$ s& R( l " [) D" U8 @% A3 ]4 @3 {$ z; a

函数名: ctrlbrk 8 ^& z7 Q: l- c t& @" J! i 功能: 设置Ctrl-Break处理程序 - Q# c( F! T1 @& ?& B' T8 Y+ W/ q) o 用法: void ctrlbrk(*fptr)(void); 7 p* b9 ]. m" V- _程序例:

#include . |9 v* K2 {1 i; k# j4 v #include

#define ABORT 0

int c_break(void) . ]) i; _% ~* N' j{ . g" S/ \8 l/ J% u4 k* r2 b( c! Nprintf("Control-Break pressed. Program aborting ...\n"); + `9 I, L- i. C( t9 E4 [ return (ABORT); & Z2 o: E( }8 G4 B4 K ?7 V- j }

int main(void) + }5 l0 B7 ^' {& {7 G { , Y& }0 q. x' P+ S' b* p ctrlbrk(c_break); 2 d* F+ e0 _; r. Y" ` for(;;) 3 b/ |7 @; q) P { ( @- `' S4 E$ I0 d6 ?; L5 Y printf("Looping... Press to quit:\n"); / H9 h* r0 ?' ]9 i! c; h} - ]* Y& O' @: |, ]; ]" M$ nreturn 0; # H1 n4 o+ G# B) e' z9 u: ^6 J+ ^ }