请教以下关于C++中友元函数的问题

来源：百度知道 编辑：UC知道 时间：2024/06/21 04:49:57
题目要求在date和time类中引用display()为友元函数 display()这在类外定义的普通函数,功能是在main()函数中输出日期和时间

以下是我写的代码 请帮忙看下问题在哪 谢谢~

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

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

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

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

void display()
{
cout<<month<<"/"<<day<<"/"<<year<<endl;
cout<<hour<<":"<<minute<<":"<<sec<<endl;
}

int main()
{
Time t1(10,13,56);
date d1(1

#include <iostream>
using namespace std;
class date;//提前声明date类
class Time
{
public:
Time(int,int,int);
friend void display(Time &,date &);
private:
int hour;
int minute;
int sec;
};

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

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

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

void display(Time &obj,date & obj2)//应该加个参数
{
cout<<obj2.month<<"/"<<obj2.day<<"/"<<obj2.year<<endl;
cout<<obj.hour<<":"<<obj.minute<<":"<<obj.sec<<endl;
}

int main()
{
Time t1(10,