【C++】基础类之日期类

1. DateClass.h

#pragma once
#include
#include
using namespace std;
class Date
{
public:
	Date(int year, int month, int day);
	Date(const Date& date)
	{
		_year = date._year;
		_month = date._month;
		_day = date._day;
	}
	void Print()
	{
		cout << "year:" << _year << "month:" << _month << "day:" << _day << endl;
	}
	//得到对应year（平年或瑞年）对应month的天数
	int GetMonthDay(int year, int month);

	//两日期比较
	bool operator>(const Date& d)const;
	bool operator==(const Date& d)const;
	bool operator<(const Date& d)const;
	bool operator>=(const Date& d)const;
	bool operator<=(const Date& d)const;
	bool operator!=(const Date& d)const;

	//日期加天数，“+=”与“+”的区别在于是否改变当前日期本身
	Date& operator+=(const int day);//改变
	Date operator+(const int day)const;//不改变

	//日期减天数，同上
	Date& operator-=(const int day);
	Date operator-(const int day)const;

	//前后置++，改变当前日期本身
	Date& operator++();//const Date& operator++();
	Date operator++(int);

	//前后置--，改变当前日期本身
	Date& operator--();
	Date operator--(int);

	//两日期间隔天数
	int operator-(const Date& date)const;

	//日期赋值
	Date& operator=(const Date& date);

	// 流插入不能写成成员函数?
	// 因为Date对象默认占用第一个参数，就是做了左操作数
	// 写出来就一定是下面这样子，不符合使用习惯
	//d1 << cout; // d1.operator<<(cout); 
	//void operator<<(ostream& out);
	/*int GetYear()
	{
		return _year;
	}*/
	friend ostream& operator<<(ostream& out, const Date& date);
	friend istream& operator>>(istream& in, Date& date);

private:
	int _year = 0;
	int _month = 0;
	int _day = 0;
};
ostream& operator<<(ostream& out, const Date& date);
istream& operator>>(istream& in, Date& date);

2. DateClass.cpp

#include"DateClass.h"
int Date::GetMonthDay(int year, int month)
{
	static int daysArr[13] = { 0,31,28,31,30,31,30,31,31,30,31,30 };
	if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0))
	{
		return 29;
	}
	else
		return daysArr[month];
}
Date::Date(int year, int month, int day)
{
	if (month > 0 && month < 13 && day < GetMonthDay(year, month))
	{
		_year = year;
		_month = month;
		_day = day;
	}
	else
	{
		cout << "非法日期" << endl;
		assert(false);
	}
}
bool Date::operator>(const Date& d)const
{
	if (_year > d._year)
	{
		return true;
	}
	if (_year == d._year && _month > d._month)
	{
		return true;
	}
	if (_year == d._year && _month == d._month && _day > d._day)
	{

		return true;
	}
	return false;
}
bool Date::operator==(const Date& d)const
{
	return _year == d._year
		&& _month == d._month
		&& _day == d._day;
}
bool Date::operator<(const Date& d)const
{
	return !(*this > d || *this == d);
}
bool Date::operator>=(const Date& d)const
{
	return *this > d || *this == d;
}
bool Date::operator<=(const Date& d)const
{
	return !(*this > d);
}
bool Date::operator!=(const Date& d)const
{
	return !(*this == d);
}
Date& Date::operator+=(const int day)
{
	if (day < 0)
	{
		return *this -= -day;
	}
	_day += day;
	while(_day > GetMonthDay(_year, _month))
	{
		_day -= GetMonthDay(_year, _month);
		_month++;
		if (_month == 13)
		{
			_year++;
			_month = 1;
		}
	}
	return *this;
}
Date Date::operator+(const int day)const
{
	Date tmp = *this;
	tmp += day;
	return tmp;
}
Date& Date::operator-=(const int day)
{
	if (day < 0)
	{
		return *this += -day;
	}
	_day -= day;
	while(_day <= 0)
	{
		_month--;
		if (_month == 0)
		{
			_year--;
			_month = 0;
		}
		_day += GetMonthDay(_year, _month);
	}
	return *this;
}
Date Date::operator-(const int day)const
{
	Date tmp = *this;
	tmp -= day;
	return tmp;
}
//const Date& Date::operator++()
//{
//	return *this + 1;
//}
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& date)const
{
	Date max = *this;
	Date min = date;
	int flag = 1;
	if (*this < date)
	{
		max = date;
		min = *this;
		flag = -1;
	}
	int count = 0;
	while (min != max)
	{
		min++;
		count++;
	}
	return count * flag;
}

Date& Date::operator=(const Date& date)
{
	if (this != &date)//注意用地址比较
	{
		_year = date._year;
		_month = date._month;
		_day = date._day;
	}

	return *this;
}

ostream& operator<<(ostream& out, const Date& date)
{
	out << "year:" << date._year << "month:" << date._month << "day:" << date._day << endl;
	return out;
}
istream& operator>>(istream& in, Date& date)
{
	int year, month, day;
	in >> year >> month >> day;
	if (month > 0 && month < 13
		&& day > 0 && day <= date.GetMonthDay(year, month))
	{
		date._year = year;
		date._month = month;
		date._day = day;
	}
	else
	{
		perror("非法日期");
		assert(false);
	}
	return in;
}

3. Text.cpp

#include"DateClass.h"
void Text1()
{
	Date d1(2024, 6, 26);
	Date d2(2024, 6, 21);

	cout << (d1 < d2) << endl; // 转换成cout << operator<(d1, d2);
	//cout << operator<(d1, d2);

	cout << (d1 < d2) << endl; // 转换成cout << d1.operator<(d2);
	//cout << d1.operator<(d2);
}
void Text2()
{
	Date d1(2024, 6, 26);
	Date d2(2024, 6, 21);
	cout << (d1 += 1);//此时输出:2024,6,27,d1被改变
	cout << (d1 + 1);//此时输出:2024,6,28，d1未被改变
	cout << (d1 -= 1);
	cout << d1++;
	cout << ++d1;
	int gap = (d2 - d1);
	cout << gap;
}
void Text3()
{
	Date d1(2024, 6, 26);
	Date d2(2024, 6, 21);
	// 已经存在的两个对象之间复制拷贝        -- 运算符重载函数
	d1 = d2;
	cout << d1;
	// 用一个已经存在的对象初始化另一个对象  -- 构造函数
	Date d3(d1);
}

int main()
{
	//Text1();
	//Text2();
	Text3();
	return 0;
}