1.头文件

定义了日期类，给出了类成员变量及成员函数的声明

#pragma once
#include<iostream>
#include<assert.h>
using namespace std;
class Date{public:friend ostream& operator<<(ostream& out, const Date& d);friend istream& operator>>(istream& in, Date& d);//判断日期是否合法void IsDayTrue()const;// 获取某年某月的天数static int GetMonthDay(int year, int month);// 全缺省的构造函数Date(int year = 1900, int month = 1, int day = 1) {IsDayTrue();_year = year;_month = month;_day = day;}// 拷贝构造函数// d2(d1)Date(const Date& d) {_year = d._year;_month = d._month;_day = d._day;}//打印日期void printf()const {cout << _year << "-" << _month << "-" << _day << endl;}// 赋值运算符重载// d2 = d3 -> d2.operator=(&d2, d3)Date& operator=(const Date& d) {if (this != &d) {this->_year = d._year;this->_month = d._month;this->_day = d._day;}return *this;}// 析构函数~Date() {}// 日期+=天数Date& operator+=(int day);// 日期+天数Date operator+(int day)const;// 日期-天数Date operator-(int day)const;// 日期-=天数Date& operator-=(int day);// 前置++Date& operator++();// 后置++Date operator++(int)const;// 后置--Date operator--(int )const;// 前置--Date& operator--();// >运算符重载bool operator>(const Date& d)const;// ==运算符重载bool operator==(const Date& d)const;// >=运算符重载bool operator >= (const Date& d)const;// <运算符重载bool operator < (const Date& d)const;// <=运算符重载bool operator <= (const Date& d)const;// !=运算符重载bool operator != (const Date& d)const;// 日期-日期 返回天数int operator-(const Date& d)const;private:int _year;int _month;int _day;};//流插入,流提取ostream& operator<<(ostream& out ,const Date& d);
istream& operator>>(istream& in, Date& d);

2.成员函数的定义

#include "date.h"void Date::IsDayTrue()const {if (_month > 0 && _month < 13 && _day>0 && _day <= GetMonthDay(_year, _month)) {return;}else {cout << "非法日期" << endl;assert(false);}
}int Date::GetMonthDay(int year, int month)  {int _month[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };if ((month == 2) && ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))) {return 29;}return _month[month];
}Date& Date::operator+=(int day) {_day += day;while (_day > GetMonthDay(_year, _month)) {_day -= GetMonthDay(_year, _month);_month++;if (_month > 12) {_year++;_month = 1;}}return *this;
}Date Date::operator+(int day)const {Date temp(*this);temp += day;return temp;
}Date& Date::operator-=(int day) {_day -= day;while (_day < 0) {_month--;_day += GetMonthDay(_year, _month);if (_month < 0) {_year--;_month = 1;}}return *this;}Date Date::operator-(int day)const {Date temp(*this);temp -= day;return temp;
}Date& Date::operator++() {*this += 1;return *this;
}Date Date::operator++(int )const {Date temp(*this);temp+=1;return temp;}Date& Date::operator--() {*this -= 1;return *this;
}Date Date::operator--(int) const{Date temp(*this);temp-=1;return temp;}bool Date::operator>(const Date& d)const {if (_year > d._year) {return true;}else if ((_year == d._year) && (_month > d._month)) {return true;}else if ((_year == d._year) && (_month == d._month) && (_day > d._day)) {return true;}return false;}bool Date::operator==(const Date& d) const {if ((_year == d._year) && (_month == d._month) && (_day == d._day)) {return true;}return false;}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);
}bool  Date::operator != (const Date& d) const {return !(*this == d);
}//int Date::operator-(const Date& d) {
//
//	int days = 0;
//	int month = _month;
//	int year = _year;
//
//	if (_day < d._day) {
//
//		_day += GetMonthDay(_year, month);
//		month--;
//	}
//
//	days = _day - d._day;
//	
//
//	if (month < d._month) {
//
//		month += 12;
//		year--;
//	}
//	
//	int x = d._month;
//
//	for (int i = d._month,y=d._year; i < month ; i++,x++) {   //控制循环次数，即计算相差几个月
//
//		if(x > 12) {    
//			x = 1;
//			y++;
//		}
//		int ret=GetMonthDay(y,x);
//		days += ret;
//
//
//	}
//
//	for (int i = d._year; i < year; i++) {
//
//		if ((i % 4 == 0 && i % 100 != 0) || (i % 400 == 0)) {
//			days += 366;
//		}
//
//		else {
//			days += 365;
//		}
//	}
//
//	return days;
//}//d1<d2,计算d1-d2int Date::operator-(const Date& d)const
{int flag = 1;Date max = *this;Date min = d;if (*this < d){max = d;min = *this;flag = -1;}int day = 0;while (min < max){++(min);++day;}return day * flag;
}ostream& operator<<(ostream& out, const Date& d) {d.IsDayTrue();out << d._year  <<"年"<< d._month << "月" << d._day << "日" << endl;return out;
}istream& operator>>(istream& in, Date& d) {in >> d._year >> d._month >> d._day;d.IsDayTrue();return in;}