C++第三次实验2.3

#include <iostream>  
using namespace std;  
class Date;
class Time
{    
public:    
    Time(int,int,int);    
    void add_a_second(Date &);  //增加1秒，1秒后可能会到了下一天，乃到下一月、下一年    
    void display(Date &);  //显示时间，格式：月/日/年 时:分:秒    
private:    
    int hour;    
    int minute;    
    int sec;    
};      
class Date    
{    
public:    
    Date(int,int,int);    
    friend class Time; //Time为Date的友元类    
private:    
    int month;    
    int day;    
    int year;    
}; 
Time::Time(int h,int m,int s)
{
	hour=h;
	minute=m;
	sec=s;
}
Date::Date(int y,int m,int d)
{
	year=y;
	month=m;
	day=d;
}  
int theDay(int y,int m)
{
	int d[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
	if((y%100==0&&y%4!=0)||(y%400==0))
		d[2]=29;
	return d[m];
} 
void Time::add_a_second(Date &d)
{
	if(++sec>=60)
		++minute,sec=sec%60;
	if(++minute>=60)
		++hour,minute=minute%60;
	if(++hour>=24)
		++d.day,hour=hour%24;
	if(d.day>theDay(d.year,d.month))
    {
		++d.month;
        d.day=1;
	}
	if(d.month>12)
		++d.year,d.month=d.month%12;
}
void Time::display(Date &d)
{
	cout<<d.year<<"/"<<d.month<<"/"<<d.day<<" ";
	cout<<hour<<":"<<minute<<":"<<sec<<endl;
}
int main( )    
{    
    Time t1(23,59,32);    
    Date d1(12,31,2013);   //测试时，再试试Date d1(2,28,2013)会如何    
    for(int i=0; i<=100; i++)    
    {    
        t1.add_a_second(d1);    
        t1.display(d1);    
    }    
    return 0;    
}    
//下面定义两个类中的成员函数，要求不得再增加成员函数    
//注意体会在Time的成员函数中可以调用Date类的私有数据成员