c.txt

C语言函数大全

/* close the file */ 
close(handle); 
} 
else 
{ 
printf("Error opening file\n"); 
} 
return 0; 
} 



函数名: clock 
功 能: 确定处理器时间 
用 法: clock_t clock(void); 
程序例: 

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

int main(void) 
{ 
clock_t start, end; 
start = clock(); 

delay(2000); 

end = clock(); 
printf("The time was: %f\n", (end - start) / CLK_TCK); 

return 0; 
} 



函数名: closegraph 
功 能: 关闭图形系统 
用 法: void far closegraph(void); 
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 x, y; 

/* initialize graphics mode */ 
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 */ 
} 

x = getmaxx() / 2; 
y = getmaxy() / 2; 

/* output a message */ 
settextjustify(CENTER_TEXT, CENTER_TEXT); 
outtextxy(x, y, "Press a key to close the graphics system:"); 

/* wait for a key */ 
getch(); 

/* closes down the graphics system */ 
closegraph(); 

printf("We're now back in text mode.\n"); 
printf("Press any key to halt:"); 
getch(); 
return 0; 
} 



函数名: clreol 
功 能: 在文本窗口中清除字符到行末 
用 法: void clreol(void); 
程序例: 

#include <conio.h> 

int main(void) 

{ 
clrscr(); 
cprintf("The function CLREOL clears all characters from the\r\n"); 
cprintf("cursor position to the end of the line within the\r\n"); 
cprintf("current text window, without moving the cursor.\r\n"); 
cprintf("Press any key to continue . . ."); 
gotoxy(14, 4); 
getch(); 

clreol(); 
getch(); 

return 0; 
} 



函数名: clrscr 
功 能: 清除文本模式窗口 
用 法: void clrscr(void); 
程序例: 

#include <conio.h> 

int main(void) 
{ 
int i; 

clrscr(); 
for (i = 0; i < 20; i++) 
cprintf("%d\r\n", i); 
cprintf("\r\nPress any key to clear screen"); 
getch(); 

clrscr(); 
cprintf("The screen has been cleared!"); 
getch(); 

return 0; 
} 



函数名: coreleft 
功 能: 返回未使用内存的大小 
用 法: unsigned coreleft(void); 
程序例: 

#include <stdio.h> 
#include <alloc.h> 

int main(void) 
{ 
printf("The difference between the highest allocated block and\n"); 
printf("the top of the heap is: %lu bytes\n", (unsigned long) coreleft()); 

return 0; 
} 


函数名: cos 
功 能: 余弦函数 
用 法: double cos(double x); 
程序例: 

#include <stdio.h> 
#include <math.h> 

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

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



函数名: cosh 
功 能: 双曲余弦函数 
用 法: dluble cosh(double x); 
程序例: 

#include <stdio.h> 
#include <math.h> 

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

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



函数名: country 
功 能: 返回与国家有关的信息 
用 法: struct COUNTRY *country(int countrycode, struct country *country); 
程序例: 

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

#define USA 0 

int main(void) 
{ 
struct COUNTRY country_info; 

country(USA, &country_info); 
printf("The currency symbol for the USA is: %s\n", 
country_info.co_curr); 
return 0; 
} 



函数名: cprintf 
功 能: 送格式化输出至屏幕 
用 法: int cprintf(const char *format[, argument, ...]); 
程序例: 

#include <conio.h> 

int main(void) 
{ 
/* clear the screen */ 
clrscr(); 

/* create a text window */ 
window(10, 10, 80, 25); 

/* output some text in the window */ 
cprintf("Hello world\r\n"); 

/* wait for a key */ 
getch(); 
return 0; 
} 



函数名: cputs 
功 能: 写字符到屏幕 
用 法: void cputs(const char *string); 
程序例: 

#include <conio.h> 

int main(void) 
{ 
/* clear the screen */ 
clrscr(); 

/* create a text window */ 
window(10, 10, 80, 25); 

/* output some text in the window */ 
cputs("This is within the window\r\n"); 

/* wait for a key */ 
getch(); 
return 0; 
} 



函数名: _creat creat 
功 能: 创建一个新文件或重写一个已存在的文件 
用 法: int creat (const char *filename, int permiss); 
程序例: 

#include <sys\stat.h> 
#include <string.h> 
#include <fcntl.h> 
#include <io.h> 

int main(void) 
{ 
int handle; 
char buf[11] = "0123456789"; 

/* change the default file mode from text to binary */ 
_fmode = O_BINARY; 

/* create a binary file for reading and writing */ 
handle = creat("DUMMY.FIL", S_IREAD | S_IWRITE); 

/* write 10 bytes to the file */ 
write(handle, buf, strlen(buf)); 

/* close the file */ 
close(handle); 
return 0; 
} 


函数名: creatnew 
功 能: 创建一个新文件 
用 法: int creatnew(const char *filename, int attrib); 
程序例: 

#include <string.h> 
#include <stdio.h> 
#include <errno.h> 
#include <dos.h> 
#include <io.h> 

int main(void) 
{ 
int handle; 
char buf[11] = "0123456789"; 

/* attempt to create a file that doesn't already exist */ 
handle = creatnew("DUMMY.FIL", 0); 

if (handle == -1) 
printf("DUMMY.FIL already exists.\n"); 
else 
{ 
printf("DUMMY.FIL successfully created.\n"); 
write(handle, buf, strlen(buf)); 
close(handle); 
} 
return 0; 
} 



函数名: creattemp 
功 能: 创建一个新文件或重写一个已存在的文件 
用 法: int creattemp(const char *filename, int attrib); 
程序例: 

#include <string.h> 
#include <stdio.h> 
#include <io.h> 

int main(void) 
{ 
int handle; 
char pathname[128]; 

strcpy(pathname, "\\"); 

/* create a unique file in the root directory */ 
handle = creattemp(pathname, 0); 

printf("%s was the unique file created.\n", pathname); 
close(handle); 
return 0; 
} 



函数名: cscanf 
功 能: 从控制台执行格式化输入 
用 法: int cscanf(char *format[,argument, ...]); 
程序例: 

#include <conio.h> 

int main(void) 
{ 
char string[80]; 

/* clear the screen */ 
clrscr(); 

/* Prompt the user for input */ 
cprintf("Enter a string with no spaces:"); 

/* read the input */ 
cscanf("%s", string); 

/* display what was read */ 
cprintf("\r\nThe string entered is: %s", string); 
return 0; 
} 



函数名: ctime 
功 能: 把日期和时间转换为字符串 
用 法: char *ctime(const time_t *time); 
程序例: 

#include <stdio.h> 
#include <time.h> 

int main(void) 
{ 
time_t t; 

time(&t); 
printf("Today's date and time: %s\n", ctime(&t)); 
return 0; 
} 



函数名: ctrlbrk 
功 能: 设置Ctrl-Break处理程序 
用 法: void ctrlbrk(*fptr)(void); 
程序例: 

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

#define ABORT 0 

int c_break(void) 
{ 
printf("Control-Break pressed. Program aborting ...\n"); 
return (ABORT); 
} 

int main(void) 
{ 
ctrlbrk(c_break); 
for(;;) 
{ 
printf("Looping... Press <Ctrl-Break> to quit:\n"); 
} 
return 0; 
}