怎样用C语言编一个关机程序

要看你使用什么操作系统
＝＝＝＝＝＝＝＝＝ for Dos =======================

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

void main( void )
{
union REGS In,Out;

In.x.ax = 0x5300; /*检查是否支持APM*/
In.x.bx = 0x0000;
int86(0x15,&In,&Out);
if( Out.x.cflag != 0)
{
printf("No APM!\n");
exit(0);
}

In.x.ax = 0x5301; /*连接到APM*/
In.x.bx = 0x0000;
int86(0x15,&In,&Out);
if( (Out.x.cflag!=0) && (Out.h.ah!=0x02))
{
printf("Connecting error!\n");
exit(0);
}

In.x.ax = 0x530e; /*通知APM所使用的版本为1.2*/
In.x.cx = 0x0102;
int86(0x15,&In,&Out);
if( (Out.x.cflag != 0)
{
printf("Ver error!\n");
exit(0);
}

In.x.ax = 0x5307; /*实现关机*/
In.x.bx = 0x0001;
In.x.cx = 0x0003;
int86(0x15,&In,&Out);
if( (Out.x.cflag != 0)
{
printf("Shutdown error