#include <REGX52.H>
void Delay(unsigned int xms)		//定义xms为无符号整型
{
	unsigned char i, j;
   while(xms)
	 {
		 
	i = 2;
	j = 239;
	do
	{
		while (--j);
	} while (--i);
	xms--;                    //xms=xms-1
 }
}

void main()
{
	while(1)
	{
		if(P3_0==0)
		{
      Delay(20);               //按下犍纽消抖，延迟20ms
			while(P3_0==0);    //检测按键是否松开
			Delay(20);
			P2_0=~P2_0;        //led与初始状态相反
		}
	}
}