友元类

来源：互联网发布：c语言死机病毒怎么处理编辑：程序博客网时间：2024/06/06 19:10
#include<iostream>using namespace std;class Date; //对Date类的提前引用声明class Time{public:    Time(int,int,int);    void add_a_second(Date &);  //增加1秒，1秒后可能会到了下一天，乃到下一月、下一年    void display(Date &);  //显示时间，格式：月/日/年 时:分:秒private:    int hour;    int minute;    int sec;};Time::Time(int x,int y,int z):hour(x),minute(y),sec(z) {}class Date{public:    Date(int,int,int);    friend class Time; //Time为Date的友元类private:    int month;    int day;    int year;};Date::Date(int x,int y,int z):month(x),day(y),year(z) {}int main( ){    int i;    Time t1(23,59,32);    Date d1(2,28,2013);    for(i=0;i<=100; i++)    {        t1.add_a_second(d1);        t1.display(d1);    }    return 0;}int judge(int y,int m);int judge(int y,int m){    int t[]= {0,31,28,31,30,31,30,31,31,30,31,30,31};    if((y%100==0&&y%4!=0)||(y%400==0)) t[2]=29;    return t[m];}void Time::add_a_second(Date &t){    sec=sec+1;    if(sec>=60)    {        minute+=1;        sec-=60;    }    if(minute>=60)    {        hour+=1;        minute-=60;    }    if(hour>24)    {        hour-=24;        t.day+=1;    }    if(t.day>judge(t.year,t.month))    {        t.day-=judge(t.year,t.month);        t.month+=1;    }    if(t.month>12)    {        t.month-=12;        t.year+=1;    }}void Time::display(Date &t){    cout<<t.year<<" "<<t.month<<" "<<t.day<<" "<<hour<<" "<<minute<<" "<<sec<<" ";}
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