Application of external interrupts

One . External interrupt 0 application

 1·k3 control LED flashing

#include"reg51.h"
typedef unsigned char u8;
typedef unsigned int u16;

 sbit led1=P2^0;
 sbit led2=P2^1;
 sbit led3=P2^2;
 sbit led4=P2^3;
 sbit led5=P2^4;
 sbit led6=P2^5;
 sbit k3=P3^2;
 void delay(u16  i)
 {
 while(i--);
 }
 void zhongduan()
 {
 EA=1;
 IT0=1;
 EX0=1;
 }
 void main()
 {
   zhongduan();
 }
 void Int0() interrupt 0
 {
   delay(1000);
   if(k3==0)
   {
   led1=~led1;
   led2=~led2;
   led3=~led3;
   led4=~led4;
   led5=~led5;
   led6=~led6;
	 
   }
 }

effect

Mistakes ：

void main()
{
void zhongduan();
}

2· Control the buzzer

#include"reg51.h"

typedef unsigned char u8;	  
typedef unsigned int u16;

sbit beep=P1^5;
sbit k3=P3^2;	   

void delay(u16 i)
{
	while(i--);	
}


void zhongduan()
{
EA=1;
IT0=0;
EX0=1;
}
void main()
{
   zhongduan();
}
void Int0() interrupt 0
{
	
if(k3==0)
	{	
		beep=~beep;
		delay(10);

	}
		   
}