谭浩强c++程序设计（第四版）书后习题答案9.10

将例9.13程序中的display函数不放在Time类中…………

#include<iostream>

using namespace std;

class Date;

class Time;

void display(Date &,Time &);

class Time{

public:

Time(int,int,int);

friend void display(Date &,Time &);

private:

int hour;

int minute;

int sec;

};

class Date{

public:

Date(int,int,int);

friend void display(Date &,Time &);

private:

int month;

int day;

int year;

};

Time::Time(int h, int m,int s)

{

hour=h;

minute=m;

sec=