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C語言函數(shù)庫 

函數(shù)大全(a開頭)



函數(shù)名: abort 
功 能: 異常終止一個(gè)進(jìn)程 
用 法: void abort(void); 
程序例: 
#include <stdio.h> 
#include <stdlib.h> 



int main(void) 
{ 
printf("Calling abort()\n"); 
abort(); 
return 0; /* This is never reached */ 
} 





函數(shù)名: abs 
功 能: 求整數(shù)的絕對值 
用 法: int abs(int i); 
程序例: 
#include <stdio.h> 
#include <math.h> 



int main(void) 
{ 
int number = -1234; 



printf("number: %d absolute value: %d\n", 
number, abs(number)); 
return 0; 
} 





函數(shù)名: absread, abswirte 
功 能: 絕對磁盤扇區(qū)讀、寫數(shù)據(jù) 
用 法: int absread(int drive, int nsects, int sectno, void *buffer); 

int abswrite(int drive, int nsects, in tsectno, void *buffer); 
程序例: 
/* absread example */ 



#include <stdio.h> 
#include <conio.h> 
#include <process.h> 
#include <dos.h> 



int main(void) 
{ 
int i, strt, ch_out, sector; 
char buf[512]; 



printf("Insert a diskette into drive A and 
press any key\n"); 
getch(); 
sector = 0; 
if (absread(0, 1, sector, &buf) != 0) 
{ 
perror("Disk problem"); 
exit(1); 
} 
printf("Read OK\n"); 
strt = 3; 
for (i=0; i<80; i++) 
{ 
ch_out = buf[strt+i]; 
putchar(ch_out); 
} 
printf("\n"); 
return(0); 
} 






函數(shù)名: access 
功 能: 確定文件的訪問權(quán)限 
用 法: int access(const char *filename, int amode); 
程序例: 
#include <stdio.h> 
#include <io.h> 



int file_exists(char *filename); 



int main(void) 
{ 
printf("Does NOTEXIST.FIL exist: %s\n", 
file_exists("NOTEXISTS.FIL") ? "YES" : "NO"); 
return 0; 
} 



int file_exists(char *filename) 
{ 
return (access(filename, 0) == 0); 
} 




函數(shù)名: acos 
功 能: 反余弦函數(shù) 
用 法: double acos(double x); 
程序例: 
#include <stdio.h> 
#include <math.h> 



int main(void) 
{ 
double result; 
double x = 0.5; 



result = acos(x); 
printf("The arc cosine of %lf is %lf\n", x, result); 
return 0; 
} 





函數(shù)名: allocmem 
功 能: 分配DOS存儲段 
用 法: int allocmem(unsigned size, unsigned *seg); 
程序例: 
#include <dos.h> 
#include <alloc.h> 
#include <stdio.h> 



int main(void) 
{ 
unsigned int size, segp; 
int stat; 



size = 64; /* (64 x 16) = 1024 bytes */ 

stat = allocmem(size, &segp); 
if (stat == -1) 
printf("Allocated memory at segment: %x\n", segp); 
else 
printf("Failed: maximum number of paragraphs available is %u\n", 

stat); 



return 0; 
} 





函數(shù)名: arc 
功 能: 畫一弧線 
用 法: void far arc(int x, int y, int stangle, int endangle, int radius); 

程序例: 
#include <graphics.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <conio.h> 



int main(void) 
{ 
/* request auto detection */ 
int gdriver = DETECT, gmode, errorcode; 
int midx, midy; 
int stangle = 45, endangle = 135; 
int radius = 100; 



/* initialize graphics and local variables 
*/ 
initgraph(&gdriver, &gmode, ""); 



/* read result of initialization */ 
errorcode = graphresult(); /* an error occurred */ 
if (errorcode != grOk) 
{ 
printf("Graphics error: %s\n", grapherrormsg(errorcode)); 
printf("Press any key to halt:"); 
getch(); 



exit(1); /* terminate with an error code 
*/ 
} 



midx = getmaxx() / 2; 
midy = getmaxy() / 2; 
setcolor(getmaxcolor()); 



/* draw arc */ 
arc(midx, midy, stangle, endangle, radius); 



/* clean up */ 
getch(); 
closegraph(); 
return 0; 
} 





函數(shù)名: asctime 
功 能: 轉(zhuǎn)換日期和時(shí)間為ASCII碼 
用 法: char *asctime(const struct tm *tblock); 
程序例: 
#include <stdio.h> 
#include <string.h> 
#include <time.h> 



int main(void) 
{ 
struct tm t; 
char str[80]; 



/* sample loading of tm structure */ 



t.tm_sec = 1; /* Seconds */ 
t.tm_min = 30; /* Minutes */ 
t.tm_hour = 9; /* Hour */ 
t.tm_mday = 22; /* Day of the Month */ 
t.tm_mon = 11; /* Month */ 
t.tm_year = 56; /* Year - does not include century */ 
t.tm_wday = 4; /* Day of the week */ 
t.tm_yday = 0; /* Does not show in asctime */ 
t.tm_isdst = 0; /* Is Daylight SavTime; does not show in asctime 
*/ 



/* converts structure to null terminated 

string */ 



strcpy(str, asctime(&t)); 
printf("%s\n", str); 



return 0; 
} 






函數(shù)名: asin 
功 能: 反正弦函數(shù) 
用 法: double asin(double x); 
程序例: 
#include <stdio.h> 
#include <math.h> 



int main(void) 
{ 
double result; 
double x = 0.5; 



result = asin(x); 
printf("The arc sin of %lf is %lf\n", x, result); 
return(0); 
} 






函數(shù)名: assert 
功 能: 測試一個(gè)條件并可能使程序終止 
用 法: void assert(int test); 
程序例: 
#include <assert.h> 
#include <stdio.h> 

#include <stdlib.h> 



struct ITEM { 
int key; 
int value; 
}; 



/* add item to list, make sure list is not 
null */ 
void additem(struct ITEM *itemptr) { 

assert(itemptr != NULL); 
/* add item to list */ 
} 



int main(void) 
{ 
additem(NULL); 
return 0; 
} 






函數(shù)名: atan 
功 能: 反正切函數(shù) 
用 法: double atan(double x); 
程序例: 
#include <stdio.h> 
#include <math.h> 



int main(void) 
{ 
double result; 
double x = 0.5; 



result = atan(x); 
printf("The arc tangent of %lf is %lf\n", x, result); 
return(0); 
} 





函數(shù)名: atan2 
功 能: 計(jì)算Y/X的反正切值 
用 法: double atan2(double y, double x); 
程序例: 
#include <stdio.h> 
#include <math.h> 



int main(void) 
{ 
double result; 
double x = 90.0, y = 45.0; 



result = atan2(y, x); 
printf("The arc tangent ratio of %lf is %lf\n", (y / x), result); 

return 0; 
} 





函數(shù)名: atexit 
功 能: 注冊終止函數(shù) 
用 法: int atexit(atexit_t func); 
程序例: 
#include <stdio.h> 
#include <stdlib.h> 



void exit_fn1(void) 
{ 
printf("Exit function #1 called\n"); 
} 



void exit_fn2(void) 
{ 
printf("Exit function #2 called\n"); 
} 



int main(void) 
{ 
/* post exit function #1 */ 
atexit(exit_fn1); 
/* post exit function #2 */ 
atexit(exit_fn2); 
return 0; 
} 






函數(shù)名: atof 
功 能: 把字符串轉(zhuǎn)換成浮點(diǎn)數(shù) 
用 法: double atof(const char *nptr); 
程序例: 
#include <stdlib.h> 
#include <stdio.h> 



int main(void) 
{ 

float f; 
char *str = "12345.67"; 



f = atof(str); 
printf("string = %s float = %f\n", str, f); 
return 0; 
} 





函數(shù)名: atoi 
功 能: 把字符串轉(zhuǎn)換成長整型數(shù) 
用 法: int atoi(const char *nptr); 
程序例: 
#include <stdlib.h> 
#include <stdio.h> 



int main(void) 
{ 
int n; 
char *str = "12345.67"; 



n = atoi(str); 
printf("string = %s integer = %d\n", str, n); 
return 0; 
} 





函數(shù)名: atol 
功 能: 把字符串轉(zhuǎn)換成長整型數(shù) 
用 法: long atol(const char *nptr); 
程序例: 



#include <stdlib.h> 
#include <stdio.h> 



int main(void) 
{ 
long l; 
char *str = "98765432"; 



l = atol(lstr); 
printf("string = %s integer = %ld\n", str, l); 
return(0); 
}



C語言函數(shù)庫 

函數(shù)大全(b開頭)



函數(shù)名: bar 

功 能: 畫一個(gè)二維條形圖 
用 法: void far bar(int left, int top, int right, int bottom); 
程序例: 



#include <graphics.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <conio.h> 



int main(void) 
{ 
/* request auto detection */ 
int gdriver = DETECT, gmode, errorcode; 
int midx, midy, i; 



/* initialize graphics and local variables 
*/ 

initgraph(&gdriver, &gmode, ""); 



/* read result of initialization */ 
errorcode = graphresult(); 
if (errorcode != grOk) /* an error occurred */ 
{ 
printf("Graphics error: %s\n", grapherrormsg(errorcode)); 
printf("Press any key to halt:"); 
getch(); 
exit(1); /* terminate with an error code */ 
} 



midx = getmaxx() / 2; 
midy = getmaxy() / 2; 



/* loop through the fill patterns */ 
for (i=SOLID_FILL; ibr> { 
/* set the fill style */ 
setfillstyle(i, getmaxcolor()); 



/* draw the bar */ 
bar(midx-50, midy-50, midx+50, 
midy+50); 



getch(); 
} 



/* clean up */ 
closegraph(); 
return 0; 
} 






函數(shù)名: bar3d 
功 能: 畫一個(gè)三維條形圖 
用 法: void far bar3d(int left, int top, int right, int bottom, 
int depth, int topflag); 
程序例: 



#include <graphics.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <conio.h> 



int main(void) 
{ 
/* request auto detection */ 
int gdriver = DETECT, gmode, errorcode; 
int midx, midy, i; 



/* initialize graphics, local variables 
*/ 
initgraph(&gdriver, &gmode, ""); 



/* read result of initialization */ 
errorcode = graphresult(); 
if (errorcode != grOk) /* an error occurred */ 
{ 
printf("Graphics error: %s\n", grapherrormsg(errorcode)); 
printf("Press any key to halt:"); 
getch(); 
exit(1); /* terminate with error code */ 
} 



midx = getmaxx() / 2; 
midy = getmaxy() / 2; 



/* loop through the fill patterns */ 
for (i=EMPTY_FILL; ibr> { 
/* set the fill style */ 
setfillstyle(i, getmaxcolor()); 



/* draw the 3-d bar */ 
bar3d(midx-50, midy-50, midx+50, midy+50, 10, 1); 



getch(); 
} 



/* clean up */ 
closegraph(); 
return 0; 
} 






函數(shù)名: bdos 
功 能: DOS系統(tǒng)調(diào)用 

用 法: int bdos(int dosfun, unsigned dosdx, unsigned dosal); 
程序例: 



#include <stdio.h> 
#include <dos.h> 



/* Get current drive as  A ,  B , ... */ 

char current_drive(void) 
{ 
char curdrive; 



/* Get current disk as 0, 1, ... */ 
curdrive = bdos(0x19, 0, 0); 
return( A  + curdrive); 
} 



int main(void) 
{ 
printf("The current drive is %c:\n", current_drive()); 
return 0; 
} 





函數(shù)名: bdosptr 
功 能: DOS系統(tǒng)調(diào)用 
用 法: int bdosptr(int dosfun, void *argument, unsigned dosal); 
程序例: 



#include <string.h> 
#include <stdio.h> 
#include <dir.h> 
#include <dos.h> 
#include <errno.h> 
#include <stdlib.h> 



#define BUFLEN 80 



int main(void) 
{ 
char buffer[BUFLEN]; 
int test; 



printf("Enter full pathname of a directory\n"); 

gets(buffer); 



test = bdosptr(0x3B,buffer,0); 
if(test) 
{ 
printf("DOS error message: %d\n", errno); 
/* See errno.h for error listings */ 
exit (1); 
} 



getcwd(buffer, BUFLEN); 
printf("The current directory is: %s\n", buffer); 



return 0; 
} 






函數(shù)名: bioscom 
功 能: 串行I/O通信 
用 法: int bioscom(int cmd, char abyte, int port); 
程序例: 



#include <bios.h> 
#include <conio.h> 



#define COM1 0 
#define DATA_READY 0x100 
#define TRUE 1 
#define FALSE 0 



#define SETTINGS ( 0x80 | 0x02 | 0x00 | 0x00) 




int main(void)