c函数大全.txt

关于c中的一些函数用法的说明

函数大全(a开头)

函数名: abort 
功 能: 异常终止一个进程 
用 法: void abort(void); 
程序例: 
#include 
#include 

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



函数名: abs 
功 能: 求整数的绝对值 
用 法: int abs(int i); 
程序例: 
#include 
#include 

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

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



函数名: absread, abswirte 
功 能: 绝对磁盘扇区读、写数据 
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 
#include 
#include 
#include 

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); 
} 




函数名: access 
功 能: 确定文件的访问权限 
用 法: int access(const char *filename, int amode); 
程序例: 
#include 
#include 

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); 
} 


函数名: acos 
功 能: 反余弦函数 
用 法: double acos(double x); 
程序例: 
#include 
#include 

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; 
} 



函数名: allocmem 
功 能: 分配DOS存储段 
用 法: int allocmem(unsigned size, unsigned *seg); 
程序例: 
#include 
#include 
#include 

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; 
} 



函数名: arc 
功 能: 画一弧线 
用 法: void far arc(int x, int y, int stangle, int endangle, int radius); 
程序例: 
#include 
#include 
#include 
#include 

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; 
} 



函数名: asctime 
功 能: 转换日期和时间为ASCII码 
用 法: char *asctime(const struct tm *tblock); 
程序例: 
#include 
#include 
#include 

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; 
} 




函数名: asin 
功 能: 反正弦函数 
用 法: double asin(double x); 
程序例: 
#include 
#include 

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); 
} 




函数名: assert 
功 能: 测试一个条件并可能使程序终止 
用 法: void assert(int test); 
程序例: 
#include 
#include 
#include 

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; 
} 




函数名: atan 
功 能: 反正切函数 
用 法: double atan(double x); 
程序例: 
#include 
#include 

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); 
} 



函数名: atan2 
功 能: 计算Y/X的反正切值 
用 法: double atan2(double y, double x); 
程序例: 
#include 
#include 

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; 
} 



函数名: atexit 
功 能: 注册终止函数 
用 法: int atexit(atexit_t func); 
程序例: 
#include 
#include 

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; 
} 




函数名: atof 
功 能: 把字符串转换成浮点数 
用 法: double atof(const char *nptr); 
程序例: 
#include 
#include 

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

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



函数名: atoi 
功 能: 把字符串转换成长整型数 
用 法: int atoi(const char *nptr); 
程序例: 
#include 
#include 

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

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



函数名: atol 
功 能: 把字符串转换成长整型数 
用 法: long atol(const char *nptr); 
程序例: 

#include 
#include 

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

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

函数大全(b开头)

函数名: bar 
功 能: 画一个二维条形图 
用 法: void far bar(int left, int top, int right, int bottom); 
程序例: 

#include 
#include 
#include 
#include 

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; i { 
/* 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; 
} 




函数名: bar3d 
功 能: 画一个三维条形图 
用 法: void far bar3d(int left, int top, int right, int bottom, 
int depth, int topflag); 
程序例: 

#include 
#include 
#include 
#include 

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; i { 
/* 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; 
} 




函数名: bdos 
功 能: DOS系统调用 
用 法: int bdos(int dosfun, unsigned dosdx, unsigned dosal); 
程序例: 

#include 
#include 

/* 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; 
} 




函数名: bdosptr 
功 能: DOS系统调用 
用 法: int bdosptr(int dosfun, void *argument, unsigned dosal); 
程序例: 

#include 
#include 
#include 
#include 
#include 
#include 

#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; 
} 




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

#include 
#include 

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

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

int main(void) 
{ 
int in, out, status, DONE = FALSE; 

bioscom(0, SETTINGS, COM1); 
cprintf("... BIOSCOM [ESC] to exit ...\n"); 
while (!DONE) 
{ 
status = bioscom(3, 0, COM1); 
if (status & DATA_READY) 
if ((out = bioscom(2, 0, COM1) & 0x7F) != 0) 
putch(out); 
if (kbhit()) 
{ 
if ((in = getch()) == '\x1B') 
DONE = TRUE; 
bioscom(1, in, COM1); 
} 
} 
return 0; 
} 




函数名: biosdisk 
功 能: 软硬盘I/O 
用 法: int biosdisk(int cmd, int drive, int head, int track, int sector 
int nsects, void *buffer); 
程序例: 

#include 
#include 

int main(void) 
{ 
int result; 
char buffer[512]; 

printf("Testing to see if drive a: is ready\n"); 
result = biosdisk(4,0,0,0,0,1,buffer); 
result &= 0x02; 
(result) ? (printf("Drive A: Ready\n")) : 
(printf("Drive A: Not Ready\n")); 

return 0; 
} 




函数名: biosequip 
功 能: 检查设备 
用 法: int biosequip(void); 
程序例: 

#include 
#include 

int main(void) 
{ 
int result; 
char buffer[512]; 

printf("Testing to see if drive a: is ready\n"); 
result = biosdisk(4,0,0,0,0,1,buffer); 
result &= 0x02; 
(result) ? (printf("Drive A: Ready\n")) : 
(printf("Drive A: Not Ready\n")); 

return 0; 
} 




函数名: bioskey 
功 能: 直接使用BIOS服务的键盘接口 
用 法: int bioskey(int cmd); 
程序例: 

#include 
#include 
#include 

#define RIGHT 0x01 
#define LEFT 0x02 
#define CTRL 0x04 
#define ALT 0x08 

int main(void) 
{ 
int key, modifiers; 

/* function 1 returns 0 until a key is pressed */ 
while (bioskey(1) == 0); 

/* function 0 returns the key that is waiting */ 
key = bioskey(0); 

/* use function 2 to determine if shift keys were used */ 
modifiers = bioskey(2); 
if (modifiers) 
{ 
printf("["); 
if (modifiers & RIGHT) printf("RIGHT"); 
if (modifiers & LEFT) printf("LEFT"); 
if (modifiers & CTRL) printf("CTRL"); 
if (modifiers & ALT) printf("ALT"); 
printf("]"); 
} 
/* print out the character read */ 
if (isalnum(key & 0xFF)) 
printf("'%c'\n", key); 
else 
printf("%#02x\n", key); 
return 0; 
} 



函数名: biosmemory 
功 能: 返回存储块大小 
用 法:int biosmemory(void); 
程序例: 

#include 
#include 

int main(void)