C :

#include<stdio.h>
int main()
{
	int year;
	scanf("%d",&year);
	if((year%4==0 && year%100!=0)||(year%400==0))
		printf("%d is a leap year!\n",year);
	else printf("%d is not a leap year!\n",year);
	getchar();
	getchar();
	return 0;
}

C++ :

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    int a;
    cin>>a;
    //如果a不能被100整除且a能被4整除，a就是闰年
    //如果a能被400整除，a就是闰年。
    if( (a%100 != 0  && a%4 == 0) || (a%400 == 0) )
    {
        cout<<a<<" is a leap year!"<<endl;
    }
    else
    {
        cout<<a<<" is not a leap year!"<<endl;
    }    
    return 0;
}