程序代码：

#include<iostream.h>
class runnian
{
public:
    runnian();
protected:
    int year;
};


runnian::runnian(int t=0)
{
    strcpy(year,t);
    if(0<t<9999)
    {
        if((t%4==0&&t%100!=0)||(t%400==0)
            cout<<t<<"是闰年"<<endl;
        else
            cout<<t<<"不是闰年"<<endl;
    }
    else
        reture ERROR:
}
int mian()
{
    runnian a;
    int y;
    cout<<"请输入一个年份："<<endl;
    cin>>y;
    a.runnian();
}