c语言库函数(o类字母).txt

内容包括: 打开一个文件用于读或写,分析文件名,使用快速排序例程进行排序,向正在执行的程序发送一个信号,改变数据段空间位置,非局部转移,以指定频率打开PC扬声器 ,正切函数,转换一个无符号长整型数为

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;  
}