C语言函数集（十三）

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;
}