C语言库函数(O类字母)

王朝c/c++·作者佚名  2008-06-01
窄屏简体版  字體: |||超大  

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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