友元函数类

 

问题及代码：

/*
 *copyright(c) 2014,烟台大学计算机学院
 *All rights reserved
 *文件名称：test.cpp
 *作者：杨昊
 *版本：v6.0
 *问题描述：友元函数类

 *输入描述：无
 *程序输出：无

*/

#include<iostream>
using namespace std;
class Date;
int a[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
class Time
{
public:
    Time(int ,int ,int );
    void add_a_second(Date&);
    void display(Date&);
private:
    int hour;
    int minute;
    int sec;
};
class Date
{
public:
    Date(int ,int ,int);
    friend class Time;
private:
    int month;
    int day;
    int year;
};
Date::Date(int m,int d,int y):month(m),day(d),year(y){}
Time::Time(int h,int m,int s):hour(h),minute(m),sec(s){}
void Time::add_a_second(Date &t)
{
    if((t.year%4==0&&t.year%100!=0)||(t.year%400==0))
        a[2]=29;
    else
        a[2]=28;
    int q;
    sec++;
    if(sec>=60)
    {
        minute=minute+sec/60;
        sec=sec%60;
    }
    if(minute>=60)
    {
        hour=hour+minute/60;
        minute=minute%60;
    }
    if(hour>=24)
    {
        q=hour/24;
        hour=hour%24;
       t.day=t.day+q;
      if(t.day>a[t.month])
        {
           t.day=t.day-a[t.month];
            t.month++;
            if(t.month>12)
            {
               t.year++;
               t.month=t.month%12;
            }
        }
    }




}
void Time::display(Date &t)
{
    cout<<t.month<<"/"<<t.day<<"/"<<t.year<<" "<<hour<<":"<<minute<<":"<<sec<<endl;
}
int main()
{
    Time t1(23,59,32);
    Date d1(12,31,2013);
    for(int i=0;i<=100;i++)
    {
        t1.add_a_second(d1);
        t1.display(d1);
    }
    return 0;
}

结果及总结：