Date.h

#pragma once
using namespace std;
#include<iostream>class Date
{friend ostream& operator<<(ostream& out, const Date& d);friend istream& operator>>(istream& in, Date& d);
public://构造函数会被频繁调用,放在类里面作为inlineDate(int year = 1900, int month = 1, int day = 1){_year = year;_month = month;_day = day;}//d1=d3Date& operator=(const Date& d)//引用作返回值,不用调用拷贝构造存临时变量{_year = d._year;_month = d._month;_day = d._day;return *this;}bool operator==(const Date& d)const;bool operator!=(const Date& d)const;bool operator>(const Date& d)const;bool operator>=(const Date& d)const;bool operator<(const Date& d)const;bool operator<=(const Date& d)const;//写在类中作为内联int GetMonthDay(int year, int month){static int days[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };int day = days[month];if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))){day += 1;}return day;}Date operator+(int day);Date& operator+=(int day);Date& operator-=(int day);Date operator-(int day);Date& operator++(int);Date& operator++();Date& operator--(int);Date& operator--();int operator-(const Date& d)const;void PrintWeekDay()const;void Print()const;private:int _year;int _month;int _day;
};inline ostream& operator<<(ostream& out, const Date& d)
{out << d._year << "/" << d._month << "/" << d._day;return out;
}inline istream& operator>>(istream& in, Date& d)
{in >> d._year >> d._month >> d._day;return in;
}

Date.cpp

#include"Date.h"
using namespace std;//任何一个类,只需要写一个> ==或者< ==重载,剩下的运算符重载复用即可
bool Date::operator==(const Date& d)const
{return _year == d._year&& _month == d._month&& _day == d._day;
}bool Date::operator!=(const Date& d)const
{/*return _year != d._year|| _month != d._month|| _day != d._day;*/return !(*this == d);
}
bool Date::operator>(const Date& d)const
{return (_year > d._year)|| ((_year == d._year) && (_month > d._month))|| (_year == d._year) && (_month == d._month) && (_day > d._day);
}
bool Date::operator>=(const Date& d)const
{return (*this > d) || (*this == d);
}
bool Date::operator<(const Date& d)const
{return !(*this >= d);
}
bool Date::operator<=(const Date& d)const
{return !(*this > d);
}Date Date::operator+(int day)
{Date ret(*this);//拷贝构造//Date ret=*this;也是拷贝构造,不是赋值,因为开始变量不存在ret += day;return ret;
}
Date& Date::operator+=(int day)//支持连续加等,所以有返回值
{_day += day;while (_day > GetMonthDay(_year, _month)){_day -= GetMonthDay(_year, _month);++_month;if (_month==13){_year++;_month = 1;}}return *this;
}void Date::Print()const
{cout << _year <<"-" << _month<<"-" << _day << endl;
}Date& Date::operator-=(int day)
{_day -= day;while (_day <= 0){_month--;if (_month == 0){_year--;_month = 12;}_day += GetMonthDay(_year, _month);}return *this;
}
Date Date::operator-(int day)
{Date ret = (*this);ret -= day;return ret;
}Date& Date::operator++(int)
{Date ret(*this);*this += 1;return ret;
}
Date& Date::operator++()
{*this += 1;return *this;
}Date& Date::operator--(int)
{Date ret(*this);*this -= 1;return ret;
}
Date& Date::operator--()
{*this += 1;return *this;
}int Date::operator-(const Date& d)const//日期减日期
{//默认第一个大,第二个小Date max = *this;Date min = d;int flag = 1;if (*this < d){max = d;min = *this;flag = -1;}int count = 0;while (min != max){min++;count++;}return count * flag;
}void Date::PrintWeekDay()const
{const char* week[] = { "周一","周二","周三","周四","周五","周六","周日" };Date start(1900, 1, 1);int count = *this-start;cout << week[count % 7] << endl;
}