C++日期类全部功能实现

Date.h

#pragma once

#include <iostream>
#include <assert.h>

using namespace std;

class Date
{
	//友元函数声明
	friend ostream& operator<<(ostream& out, const Date& d);
	friend istream& operator>>(istream& in,  Date& d);
public:
	//打印日期
	void Print() 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);

	// 析构函数
	~Date();

	// 拷贝构造函数
  // d2(d1)
	Date(const Date& d);

	// 赋值运算符重载
		// d2 = d3 -> d2.operator=(&d2, d3)
	Date& operator=(const Date& d);

	// 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);

	// 后置--
	Date operator--(int);

	// 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);
private:
	int _year;
	int _month;
	int _day;
};

//流插入
ostream& operator<<(ostream& out, const Date& d);
//流提取
istream& operator>>(istream& in, Date& d);

Date.cpp

#define _CRT_SECURE_NO_WARNINGS 1
#include "date.h"

//打印日期
void Date::Print() const
{
	cout << _year << '-' << _month << '-' << _day << endl;
}
//获取某年某月的天数
int Date::GetMonthDay(int year, int month) 
{
	int a[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
	if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
	{
		a[2] = 29;
	}
	return a[month];
}


// 全缺省的构造函数
Date::Date(int year, int month, int day)
{
	if (month >= 1 && month <= 12
		&& day >= 1 && day <= GetMonthDay(year, month))
	{
		_year = year;
		_month = month;
		_day = day;
	}
	else
	{
		cout << "日期错误"<<endl;
		assert(false);
	}
}

// 析构函数
Date::~Date()
{
	_year = 1;
	_month = 1;
	_day = 1;
}

// 拷贝构造函数
// d2(d1)
Date::Date(const Date& d)
{
	_year = d._year;
	_month = d._month;
	_day = d._day;
}

//赋值运算符重载  //已经存在的两个对象之间的复制拷贝
// d2 = d3 -> d2.operator=(&d2, d3)
Date& Date::operator=(const Date& d)
{
	if (this != &d)
	{
		this->_year = d._year;
		this->_month = d._month;
		this->_day = d._day;
	}
	return *this;
}

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

// 日期+天数
Date Date::operator+(int day) const
{
	Date tmp(*this);
	tmp += day;

	return tmp;
}

// 日期-=天数
Date& Date::operator-=(int day)
{
	if (day < 0)
	{
		*this += -day;
	}
	else
	{
		_day -= day;
		while (_day <= 0)
		{
			_month--;
			if (_month == 0)
			{
				_year--;
				_month = 12;
			}
			_day += GetMonthDay(_year, _month);
		}
	}
	return *this;
}

// 日期-天数
Date Date::operator-(int day) const
{
	Date tmp(*this);
	tmp -= day;

	return tmp;
}


// 前置++
Date& Date::operator++()
{
	return *this += 1;
}

// 后置++
Date Date::operator++(int)
{
	Date tmp(*this);
	*this += 1;
	return tmp;
}

// 前置--
Date& Date::operator--()
{
	return *this -= 1;
}

// 后置--
Date Date::operator--(int)
{
	Date tmp(*this);
	*this -= 1;

	return tmp;
}

// >运算符重载
bool Date::operator>(const Date& d) const
{
	if (_year > d._year ||
		(_year == d._year && _month > d._month) ||
		(_year == d._year && _month == d._month && _day > d._day))
	{
		return true;
	}

	return false;
}

// ==运算符重载
bool Date::operator==(const Date& d) const
{
	return _year == d._year && _month == d._month && _day == d._day;
}


// >=运算符重载
bool Date::operator >= (const Date& d) const
{
	return *this > d || *this == d;
}

// <运算符重载
bool Date::operator < (const Date& d) const
{
	return !(*this >= d);
}

// <=运算符重载
bool Date::operator <= (const Date& d) const
{
	return !(*this > d);
}

// !=运算符重载
bool Date::operator != (const Date& d) const
{
	return !(*this == d);
}

// 日期-日期 返回天数
int Date::operator-(const Date& d)
{
	int flag = -1;
	Date max = d;
	Date min = *this;
	if (*this > d)
	{
		max = *this;
		min = d;
		flag = 1;
	}
	int sum = 0;
	while (max > min)
	{
		min++;
		sum++;
	}
	return sum * flag;

}

//流插入
ostream& operator<<(ostream& out, const Date& d)
{
	out << d._year << "年" << d._month << "月" << d._day << "日" << endl;
	return out;
}
//流提取
istream& operator>>(istream& in, Date& d)
{
	int year=0, month=0, day=0;
	in >> year >> month >>day;
	if (month >= 1 && month <= 12
		&& day >= 1 && day <= Date::GetMonthDay(year, month))
	{
		d._year = year;
		d._month = month;
		d._day = day;
	}
	else
	{
		cout << "日期非法";
		assert(false);
	}
	return in;
}

test.cpp

#include "date.h"
int main()
{
	Date d1(2102, 5, 12);
	Date d2(2052, 12, 1);
	Date d3(2012, 8, 1);
	d1.Print();
	d1.operator+=(100);
	d1.Print();
	d1.operator+=(-50);
	d1.Print();
	cout << d1;
	//从左往右
	cout << d1 << d2 << d3;
	cin >> d1 >> d2;
	cout << d1 << d2 << endl;


}

}