【C++中日期类的实现】

一路，一路，一路从泥泞到风景...............................................................................................

前言

一、【什么是日期类】

二、【代码实现】

1.【Date.h】部分：

2.【Date.cpp】部分：

3.【Test.cpp】部分：

总结

前言

本篇是日期类的编写，望多多指正。

一、【什么是日期类】

在学习完类和对象之后，可以试着编写一个日期类进行练习，使得该类能够加减天数，计算两个日期之间相差的天数，还可以比较两个类之间的大小。

二、【代码实现】

1.【Date.h】部分：

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <iostream>
#include <stdbool.h>
#include <assert.h>
using namespace std;
class Date
{
public:
	friend ostream& operator<<(ostream& out, const Date& d);
	friend istream& operator>>(istream& in, Date& d);
	int GetMonthDay(int year, int month);
	Date(int year = 1, int month = 1, int day = 1);
	Date(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);
	bool operator!=(const Date& d);
	Date& operator+=(int day);
	Date operator+(int day)const;
	Date operator-(int day)const;
	Date& operator-=(int day);
	Date& operator++();
	Date operator++(int);
	Date operator--(int);
	Date& operator--();
	int operator-(const Date& d);
private:
	int _year;
	int _month;
	int _day;
};

2.【Date.cpp】部分：

#include "Date.h"
int Date::GetMonthDay(int year, int month)
{
	const static int MonthDay[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 MonthDay[month];
}
Date::Date(int year, int month, int day)
{
	_year = year;
	_month = month;
	_day = day;
	if (year < 1 || month < 1 || month>12 || day<1 || day>GetMonthDay(year,month))
	{
		cout << "error date" << endl;
		exit(-1);
	}
}
Date::Date(const Date& d)
{
	_year = d._year;
	_month = d._month;
	_day = d._day;
}
bool Date::operator<(const Date& d)
{
	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;
	}
	else
	{
		return false;
	}
}
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) || (*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 !(*this == d);
}
Date& Date::operator+=(int day)
{
	if (day < 0)
	{
		return *this -= (-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 tmp(*this);
	tmp += day;
	return tmp;
}
//Date Date::operator-(int day)
//{
//	Date tmp(*this);
//	tmp._day -= day;
//	while (tmp._day <= 0)
//	{
//		tmp._month--;
//		if (tmp._month < 1)
//		{
//			tmp._year--;
//			tmp._month = 12;
//		}
//		tmp._day += tmp.GetMonthDay(tmp._year, tmp._month);
//	}
//	return tmp;
//}
//Date& Date::operator-=(int day)
//{
//	*this = *this - day;
//	return *this;
//}


Date& Date::operator-=(int day)
{
	if (day < 0)
	{
		return *this += (-day);
	}

	_day -= day;

	while (_day <= 0)
	{
		--_month;
		if (_month == 0)
		{
			--_year;
			_month = 12;
		}

		_day += GetMonthDay(_year, _month);
	}

	return *this;
}

Date Date::operator-(int day) const
{
	Date tmp(*this);

	tmp -= day;

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

Date Date::operator++(int)
{
	Date tmp(*this);

	*this += 1;

	return tmp;
}


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

Date Date::operator--(int)
{
	Date tmp(*this);

	*this -= 1;

	return tmp;
}
int Date::operator-(const Date& d)
{
	Date Max = *this;
	Date Min = d;
	int flag = 1;
	if (*this < d)
	{
		Max = d;
		Min = *this;
		flag = -1;
	}
	int n = 0;
	while (Min != Max)
	{
		Min++;
		n++;
	}
	return flag * n;

}
ostream& operator<<(ostream& out, const Date& d)
{
	out << d._year << "/" << d._month << "/" << d._day << endl;

	return out;
}

istream& operator>>(istream& in, Date& d)
{
	in >> d._year >> d._month >> d._day;
	return in;
}

3.【Test.cpp】部分：

#define _CRT_SECURE_NO_WARNINGS
#include "Date.h"
int main()
{
	Date d1(2023,7,1);
	Date d2(2023, 7, 28);
	cout << d1 << endl;
	cout << d2 << endl;
	cout << (d2-d1) << endl;
	cout << (++d2) << endl;
	cout << (d2++) << endl;
	cout << d2 << endl; 
	cout << (d1--) << endl;
	cout << (--d1) << endl;
	Date sum = d2 + 260;
	cout << sum << endl;
	cout << (d2+=480) << endl;
	return 0;
}