c函数之o.txt

详细介绍了c语言常用函数,希望能给大家帮助!

 函数名: open 
功 能: 打开一个文件用于读或写 
用 法: int open(char *pathname, int access[, int permiss]); 
程序例: 

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

int main(void) 
{ 
int handle; 
char msg[] = "Hello world"; 

if ((handle = open("TEST.$$$", O_CREAT | O_TEXT)) == -1) 
{ 
perror("Error:"); 
return 1; 
} 
write(handle, msg, strlen(msg)); 
close(handle); 
return 0; 
} 



函数名: outport 
功 能: 输出整数到硬件端口中 
用 法: void outport(int port, int value); 
程序例: 

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

int main(void) 
{ 
int value = 64; 
int port = 0; 

outportb(port, value); 
printf("Value %d sent to port number %d\n", value, port); 
return 0; 
} 



函数名: outportb 
功 能: 输出字节到硬件端口中 
用 法: void outportb(int port, char byte); 
程序例: 

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

int main(void) 
{ 
int value = 64; 
int port = 0; 

outportb(port, value); 
printf("Value %d sent to port number %d\n", value, port); 
return 0; 
} 



函数名: outtext 
功 能: 在视区显示一个字符串 
用 法: void far outtext(char far *textstring); 
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; 

/* 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; 

/* move the C.P. to the center of the screen */ 
moveto(midx, midy); 

/* output text starting at the C.P. */ 
outtext("This "); 
outtext("is "); 
outtext("a "); 
outtext("test."); 

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



函数名: outtextxy 
功 能: 在指定位置显示一字符串 
用 法: void far outtextxy(int x, int y, char *textstring); 
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; 

/* 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; 

/* output text at the center of the screen*/ 
/* Note: the C.P. doesn't get changed.*/ 
outtextxy(midx, midy, "This is a test."); 

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


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