Date（日期类）的实现

头文件（.h）

#pragma once
class Date
{
public:
	Date(int year = 1900, int month = 1, int day = 1);


	// Date(const Date& d);
	// Date& operator=(const Date& d);
	// ~Date();

	bool operator>(const Date& d);
	bool operator<(const Date& d);
	bool operator<=(const Date& d);
	bool operator>=(const Date& d);
	bool operator==(const Date& d);
	bool operator!=(const Date& d);

	Date operator+(int day);
	Date& operator+=(int day);
	Date operator-(int day);
	Date& operator-=(int day);
	int operator-( Date& d);
	Date operator++(); // ++d => d.operator++(&d)
	Date operator++(int); // d++ => d.operator(&d, 0);
	Date operator--(); // --d 
	Date operator--(int); // d--

	int GetMonthDay(int year, int month);
	void Display();
	friend istream& operator>>(istream& is, Date &d);
	

	friend ostream& operator<<(ostream& os, const Date &d);
	
private:
	int _year;
	int _month;
	int _day;
};

Date函数（主函数）

#include"Date.h"
#include<iostream>
using namespace std;
int Date::GetMonthDay(int year, int month)
{
	static const int Monthday[] = { 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 Monthday[month];
}
Date::Date(int year,int month,int day)
{
	if (year >= 0
		&& month > 0 && month < 13
		&& day > 0 && day <= GetMonthDay(year, month))
	{
		_year = year;
		_month = month;
		_day = day;
	}
	else
	{
		//assert(false);
		std::cout << "Date Invalid" << std::endl;
	}
}
bool Date::operator>(const Date& d)
{
	if (_year > d._year)
	{
		return true;
	}
	else if (_year == d._year)
	{
		if (_month > d._month)
		{
			return true;
		}
		else if (_month == d._month)
		{
			if (_day > d._day)
			{
				return true;
			}
		}
	}
	return false;
}
bool Date::operator<(const Date& d)
{
	return !(*this >= d);
}

bool Date::operator<=(const Date& d)
{
	return !(*this > d);
}
bool Date::operator>=(const Date& d)
{
	return !(*this < d);
}
bool Date::operator==(const Date& d)
{
	return (_year == d._year) &&
		(_month == d._month)&&
		(_day == d._day);
}

bool Date::operator!=(const Date& d)
{
	return !(*this == d);
}
Date Date::operator+(int day)
{
	Date ret(*this);
	ret._day += day;

	while (ret._day > GetMonthDay(ret._year, ret._month))
	{
		ret._day -= GetMonthDay(ret._year, ret._month);
		ret._month++;
		while (ret._month > 12)
		{
			ret._month -= 12;
			ret._year++;
		}
	}

	return ret;
}
Date& Date::operator+=(int day)
{

	(*this) = (*this) + day;
	return *this;
}
Date Date::operator-(int day)
{
	Date ret(*this);
	ret._day -= day;
	while (ret._day <= 0)
	{
		ret._day += GetMonthDay(ret._year, ret._month);
			ret._month--;
			while (ret._month < 1)
			{
				ret._year--;
				ret._month += 12;
			}
	}
	return ret;
}
Date& Date::operator-=(int day)
{
	(*this) =(*this)- day;
	return *this;
}
int Date::operator-( Date& d)
{
	int day = 0;
	while (!(*this == d))
	{
		if (*this > d)
		{
			d++;
			day++;
		}
		else
		{
			d--;
			day--;
		}
	}
	return day;
}
Date Date::operator++() // ++d => d.operator++(&d)
{
	(*this)++;
	return *this;
}
Date Date::operator++(int)// d++ => d.operator(&d, 0);
{
	Date ret(*this);
	(*this) += 1;
	return ret;
}
Date Date::operator--() // --d 
{
	(*this)--;
	return *this;

}
Date Date::operator--(int) // d--
{
	Date ret(*this);
	(*this) -= 1;
	return ret;
}
istream& operator>>(istream& is, Date &d)
{
	cout << "请输入一个日期" << endl;
	is >> d._year >> d._month >> d._day;
	return is;
}
ostream& operator<<(ostream& os, const Date &d)
{
	cout << d._year << "-" << d._month << "-" << d._day << endl;
	return os;
}
void Date::Display()
{
	cout << _year << "-" << _month << "-" << _day << endl;
}

main函数（测试函数）

#include "Date.h"
#include<iostream>
using namespace std;

int main()
{
	Date d1(2018, 10, 30),d2;
 	d2 = d1++;
	cout << d2<< endl;
	return 0;
}

注意：测试代码中的cout函数要重载必须重载