C++逐步介绍日期类的使用

#pragma once
#include<iostream>
using std::cout;
using std::endl;
using std::cin;
class Date
{
public:
	//定义构造函数
	Date(int year = 1900, int month = 1, int day = 1);
	//打印日期
	void Print()
	{
		cout << _year <<" " <<_month<<" " << _day << endl;
	}
	//运算符重载
	Date operator+(int day);
	Date operator-(int day);
	Date& operator+=(int day);
	Date& operator-=(int day);
	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++();//前置
	Date operator++(int);//后置
	Date& operator--();//前置
	Date operator--(int);//后置
	int operator-(Date d);//计算两个日期的差值
private:
	int _year;
	int _month;
	int _day;
};

inline int GetMonthDay(int year, int month)
{
	//多次调用的时候static能极大减小内存消耗，但是也可以删除，并不影响程序运行
	static int _monthArray[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
	int day = _monthArray[month];
	if (month == 2 && (year % 4 == 0 && year % 100 != 0) || year % 400 == 0)//判断是否是闰年
	{
		day = 29;
	}
	return day;
}
Date::Date(int year, int month, int day)
{
	_year = year;
	_month = month;
	_day = day;
	if (!(year >= 0 && month >= 1 && month <= 12 && day > 0 && day <= GetMonthDay(year, month)))//看日期是否合法
	{
		cout << "fail" << endl;
        exit(-1);
	}
}

Date Date::operator+(int day)
{
	Date tmp(*this);
	tmp._day += day;
	//判断天数是否大于当月的天数
		while (tmp._day > GetMonthDay(tmp._year, tmp._month))
		{
			tmp._day -= GetMonthDay(tmp._year, tmp._month);
			tmp._month++;
			//判断月数是否大于12
			if (tmp._month > 12)
			{
		        tmp._year++;
				tmp._month = 1;
			}
		}
		return tmp;
}

Date& Date::operator+=(int day)
{
	Date ret(*this);
		ret._day += day;
		//判断天数是否超越了当月的天数
		while (_day > GetMonthDay(_year, _month))
		{
			_day -= GetMonthDay(_year, _month);
			_month++;
			//判断月数是否超过了12
			if (_month > 12)
			{
				_year++;
				_month = 1;
			}
		}
	}
	return *this;
}

Date Date::operator+(int day)
{
	Date tmp(*this);
	tmp += day;//直接调用operator的+=
		return tmp;
}

#define _CRT_SECURE_NO_WARNINGS 1
#include"date.h"
inline int GetMonthDay(int year, int month)
{
	static int _monthArray[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
	int day = _monthArray[month];
	if (month == 2 && (year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
	{
		day = 29;
	}
	return day;
}
Date::Date(int year, int month, int day)
{
	_year = year;
	_month = month;
	_day = day;
	if (!(year >= 0 && month >= 1 && month <= 12 && day > 0 && day <= GetMonthDay(year, month)))
	{
		cout << "!legal" << endl;
	}
}
Date& Date::operator+=(int day)
{
	if (day < 0)
	{
		*this -= -day;
	}
	else {
		_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)
{
	if (day < 0)
	{
		*this += -day;
	}
	else {
		_day -= day;
		while (_day <= 0)
		{
			if (_month == 1)
			{
				--_year;
				_month = 12;
				_day += GetMonthDay(_year, _month);
			}
			else
			{
				--_month;
				_day += GetMonthDay(_year, _month);
			}
		}
	}
	return *this;
}
Date Date::operator+(int day)
{
	Date tmp(*this);
	tmp += day;
		return tmp;
}
Date Date::operator-(int day)
{
	Date tmp(*this);
	tmp -= day;
		return tmp;
}
Date& Date::operator++()//前置
{
	return 	*this += 1;;
}
Date  Date::operator++(int)//后置
{
	Date tmp(*this);
	*this += 1;
	return tmp;
}
Date& Date::operator--()//前置
{
	return *this -= 1;
}
Date  Date::operator--(int)//后置
{
	Date tmp(*this);
	*this -= 1;
	return tmp;
}
bool Date::operator>(const Date& d)
{
	if (_year > d._year)
		return true;
	else if (_year < d._year)
		return false;
	else//_year < d._year
	{
		if (_month > d._month)
			return true;
		else if (_month < d._month)
			return false;
		else//_month < d._month
		{
			if (_day > d._day)
				return true;
			else
				return false;
		}
	}
}
bool  Date::operator<(const Date& d)
{
	return !(*this > d || *this == d);
}
bool Date::operator>=(const Date& d)
{
	return  *this > d || *this == d;
}
bool Date::operator<=(const Date& d)
{
	return !(*this > d);
}
bool  Date::operator==(const Date& d)
{
	if (_year == d._year)
	{
		if (_month == d._month)
		{
			if (_day == d._day)
				return true;
		}
	}
	return false;
}
bool  Date::operator!=(const Date& d)
{
	//复用==
	return !(*this == d);
}
int Date::operator-(Date d)
{
	int count = 0;
	Date tmp(*this);
	if (tmp < d)
	{
		while (tmp != d)
		{
			++count;
			tmp += 1;
		}
	}
	else if (tmp > d)
	{
		while (tmp != d)
		{
			--count;
			tmp -= 1;
		}
	}
	return count;
}