P121 11

<img src="https://img-blog.youkuaiyun.com/20150420134452118?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvWXVTb25nNDg2OQ==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />#include <iostream> 
using namespace std; 
class Time; 
class Date 
{public:  
Date(int,int,int); 
friend Time; 
private:  
int month; 
int day; 
int year; 
}; 
Date::Date(int m,int d,int y):month(m),day(d),year(y){ } 
class Time 
{public:  
Time(int,int,int);  
void display(const Date &); 
private: 
int hour; 
int minute; 
int sec; 
}; 
Time::Time(int h,int m,int s):hour(h),minute(m),sec(s){ } 
void Time::display(const Date &d) 
{  
cout<<d.month<<"/"<<d.day<<"/"<<d.year<<endl;  
cout<<hour<<":"<<minute<<":"<<sec<<endl; 
} 
int main() 
{  
Time t1(10,13,56); 
Date d1(12,25,2004); 
t1.display(d1); 
return 0; 
}