日期类的实现

//完善日期类，需要辅助操作可自行添加。#include<iostream>using namespace std;class Date{public:    Date(int year = 2017, int month = 9, int day = 10)        : _year(year)        , _month(month)        , _day(day)    {}    Date& operator=(const Date& d)    {        if (this != &d)         {            _year = d._year;            _month = d._month;            _day = d._day;        }        return *this;    }    //获得某月的天数    int Getmonthday(int _year, int _month)    {        //闰年        if (((_year % 4 == 0) && (_year % 100 != 0)) || (_year % 400 == 0))        {            if (_month == 1 || _month == 3 || _month == 5 || _month == 7 || _month == 8 || _month == 10 || _month == 12)            {                return 31;            }            else if (_month == 2)            {                return 29;            }            else            {                return 30;            }        }        else//平年        {            if (_month == 1 || _month == 3 || _month == 5 || _month == 7 || _month == 8 || _month == 10||_month==12)            {                return 31;            }            else if (_month == 2)            {                return 28;            }            else            {                return 30;            }        }    }    //判断日期是否合法     bool IsInvalid(int year, int month, int day)//判断日期是否合法    {        //此处从1900年开始，如果小于这个日期，则返回fasle        return ((year > 1900) && (month > 0) && (month<13) && (day>0) && (day < Getmonthday(year, month)));    }    // 前置++     Date& operator++()    {        _day += 1;        return *this;    }    // 后置++     Date operator++(int)    {        Date temp(*this);        _day += 1;        return temp;    }    Date& operator--()    {        _day -= 1;        return *this;    }    Date operator--(int)    {        Date temp(*this);        _day -= 1;        return temp;    }    //days天之后的日期     Date operator+(int days)    {        _day += days;        return *this;    }    // days天之前的日期     Date operator-(int days)    {        _day -= days;        return *this;    }    // 两个日期之间的距离     int operator-(const Date& d)    {        Date maxDate = *this;        Date minDate = d;        if (maxDate < minDate)        {            maxDate = d;            minDate = *this;        }        int days = 0;        while (minDate!= maxDate)        {            ++minDate;            days++;        }        return days;    }    /*while (1) {                    if (minDate + days == maxDate)                            break;                    days++;        }            return days;*/    bool operator==(const Date& d)    {        return (_year = d._year)&&            (_month = d._month)&&            (_day = d._day);    }    bool operator!=(const Date& d)    {        return (_year != d._year) ||            (_month != d._month) ||            (_day != d._day);    }    bool operator>(const Date& d)    {        if ((d._year < _year) || (d._month < _month) || (d._day < _day))        {            return true;        }        else            return false;    }    bool operator<(const Date& d)    {        if ((d._year > _year) || (d._month > _month) || (d._day > _day))        {            return true;        }        else            return false;    }    void display()    {        cout << _year << "-"<<_month << "-"<<_day << endl;    }    ~Date()    {}private:    int _year;    int _month;    int _day;};  int main(){    Date c1;    c1.display();    Date c2(2017, 9, 11);    c2.display();    Date c3;    c3 = c2;    c3.display();    c3 = c1++;    c3.display();    c3 = ++c1;    c3.display();    cout << "对日期减天数" << endl;       cout<< (c3-c2)<<endl;       Date c4 = c1+ 30;          Date c5;       c5.IsInvalid(2017, 1, 36);       c5.display();    bool state;        cout << "两日期比较" << endl;        Date d4(2016, 10, 9);        Date d5(2016, 10, 10);       state = (d4<d5);       cout << state << endl;       state = (d4==d5);       cout << state << endl;       state = (d4 != d5);       cout << state << endl;    system("pause");}//扩展：//1、可在日期类中添加星期//2、按照日历的形式显式日期//3、可以显式上个月下个月类似日历的翻页//4、……

运行结果为：