C++实现日期类的实现（Date）

#include<iostream>
#include<stdlib.h>
using namespace std;
class Date
{
public:
	//构造函数
	Date(int year = 1900, int month = 1, int day = 1)
		:_year(year)
		, _month(month)
		, _day(day)
	{
		if (!IsInvalidDate(_year, _month, _day))
		{
			_year = 1900;
			_month = 1;
			_day = 1;
		}
	}
	//拷贝函数
		Date(const Date& d)
		: _year(d._year)
		, _month(d._month)
		, _day(d._day)
	{}

	//析构函数
		~Date()
		{}

		//判断是不是闰年
		bool IsLeapYear(int year)
		{
			if ((year % 400 == 0) ||
				((year % 4 == 0) && (year % 100 != 0)) )
			{
				return true;
			}
			return false;
		}
		//判断是不是合法日期
		bool IsInvalidDate(int year, int month, int day)
		{
			if ((year < 1) ||
				(month < 0 || month >12) ||
				(day < 0 || day > YearsOfMonth(year, month)))
			{
				return false;
			}
			return true;
		}
		//判断当前月份多少天
		int YearsOfMonth(int year, int month)
		{
			int day;
			int days[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
			day = days[month];
			if (month == 2 && IsLeapYear(year))
			{
				day += 1;
			}
			return day;
		}
		//修正日期
		Date ToCorrect(Date &d)
		{
			while (d._day > YearsOfMonth(d._year, d._month) || d._day <= 0)
			{
				if(d._day <= 0)
				{
					d._day += YearsOfMonth(d._year,( d._month - 1));
					if (d._month == 1)
					{
						d._month = 12;
						d._year--;
					}
					else
					{
						d._month--;
					}
				}
				else
				{
					d._day -= YearsOfMonth(d._year, d._month);
					if (d._month == 12)
					{
						d._year++;
						d._month = 1;
					}
					else
					{
						d._month++;
					}
				}
			}
			return d;
		}
	// 当前日期days天后是什么日期？ 
		Date operator+(int days)
		{
			Date tmp(*this);
			tmp._day += days;
			ToCorrect(tmp);
			return tmp;
		}

	// 当前日期days天前是什么日期？ 
		Date operator-(int days)
		{
			Date tmp(*this);
			tmp._day -= days;
			ToCorrect(tmp);
			return tmp;
		}

	// 日期比大小 
	bool operator>(const Date& d)
	{
		return ( _year > d._year || 
			(_year == d._year && _month > d._month) ||
			(_year == d._year && _month == d._month && _day > d._day));
	}
	bool operator<(const Date& d)
	{
		return (_year < d._year ||
			(_year == d._year && _month < d._month) ||
			(_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)
	{
		return !(*this == d);
	}
	bool operator>=(const Date &d)
	{
		return !(*this<d);
	}
	bool operator<=(const Date &d)
	{
		return !(*this>d);
	}
	
	// 重载取地址符号 
	Date* operator&()
	{
	
	}

	// 前置++ 
	Date& operator++()
	{
		(*this)++;
		return *this;
	}

	// 后置++ 
	Date operator++(int)//通过返回值和传参区别前置和后置++
	{
		Date tmp(*this);
		(*this) = (*this) + 1;
		return tmp;
	}

	// 前置-- 
	Date& operator--()
	{
		(*this)--;
		return *this;
	}

	// 后置-- 
	Date operator--(int)
	{
		Date tmp(*this);
		(*this)--;
		return tmp;
	}
	void Display()
	{
		cout << _year << "-" << _month << "-" << _day << endl;
	}
private:
	int _year;
	int _month;
	int _day;
};

int main()
{
	Date d(2018, 9, 9);
	d.Display();
	Date d1 = d + 50;
	d1.Display();
	d1 =d1 - 50;
	d1.Display();
	
	cout << "------"<<endl;
	cout << "前置++" << endl;
	d1.Display();
	(++d1).Display();
	d1.Display();
	cout << "后置++" << endl;
	d1.Display();
	(d1++).Display();
	d1.Display();
	cout << "------" << endl;


	system("pause");
	return 0;
}