友元成员函数

#include<iostream>
using namespace std;
class Date;
class Time
{
public:
Time(int,int,int);
void display(Date&);
private:
int hour;
int minute;
int sec;
};

class Date
{
public:
Date(int,int,int);
friend void Time::display(Date&);
private:
int month;
int day;
int year;
};

Time::Time(int h,int m,int s)
{
hour=h;
minute=m;
sec=s;
}

void Time::display(Date& t)
{
cout<<t.month<<"-"<<t.day<<"-"<<t.year<<endl;
cout<<hour<<":"<<minute<<":"<<sec<<endl;
}

Date::Date(int m,int d,int y)
{
month=m;
day=d;
year=y;
}

int main()
{
Time t(12,35,59);
Date d(5,17,2011);
t.display(d);
return 0;
}