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; 
}