【C++课程学习】：Data类的实现

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🍩1.头文件

🍩2.实现文件：

🍩3.分析：

🍟3.1Data的构造函数和析构函数：

🍟3.2拷贝构造：

前言：
类学的差不多的，我们就日期类来对前面类的学习做一个巩固，然后学习一下运算符重载。

🍩1.头文件

#pragma once
#include<iostream>
#include<stdbool.h>
#include<assert.h>
#include<math.h>
using namespace std;

class Data {
	friend ostream& operator<<(ostream& out, Data& d);
	friend istream& operator>>(istream& in, Data& d);
public:
	//全缺省的构造函数
	Data(int year = 1, int month = 1, int day = 1) {
		_year = year;
		_month = month;
		_day = day;
	}
	//拷贝构造函数
	Data(const Data& d)
	{
		_year = d._year;
		_month = d._month;
		_day = d._day;
	}
	//运算符重载
	bool operator==(const Data& d);
	bool operator<(const Data& d);
	bool operator>(const Data& d);
	bool operator<=(const Data& d);
	bool operator>=(const Data& d);
	bool operator!=(const Data& d);
	Data& operator = (const Data& d);

	//日期+天数
	Data& operator+=(int day);
	Data operator+(int day);

	//日期-天数
	Data& operator-=(int day);
	Data operator-(int day);

	//日期的前置和后置++
	Data& operator++();
	Data operator++(int);

	//日期的前置和后置--
	Data& operator--();
	Data operator--(int);

	//日期减日期=相差的天数
	int operator-(const Data& d);

	//void operator<<(ostream& out);


	//内联函数，获取year年第month的天数
	int GetDay(int year, int month) {
		assert(month > 0 && month < 13);
		static int days[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
		//闰年的二月返回29
		if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0))
			return 29;
		return days[month];
	}
	void print() {
		cout << _year << "-" << _month << "-" << _day << endl;
	}

	int Getyear() {
		return _year;
	}
	int Getmonth() {
		return _month;
	}
	int Getday() {
		return _day;
	}
	//析构函数
	~Data() {
		_year = -1;
		_month = -1;
		_day = -1;
	}
private:
	int _year;
	int _month;
	int _day;
};

🍩2.实现文件：

#include"Data.h"
bool Data::operator==(const Data& d) {
	return _year == d._year
		&& _month == d._month
		&& _day == d._day;
}

bool Data::operator<(const Data& d) {
	if (_year < d._year)
	{
		return true;
	}
	else if (_year == d._year)
	{
		if (_month < d._month)
		{
			return true;
		}
		else if (_month == d._month)
		{
			if (_day < d._day)
			{
				return true;
			}
		}
	}
	return false;
}

bool Data::operator<=(const Data& d) {
	return (*this == d) || (*this < d);
}

bool Data::operator>(const Data& d) {
	return !(*this <= d);
}

bool Data::operator>=(const Data& d) {
	return (*this == d) || (*this) > d;
}
bool Data::operator!=(const Data& d) {
	return !(*this == d);
}

Data& Data::operator = (const Data& d) {
	_year = d._year;
	_month = d._month;
	_day = d._day;
	return *this;
}

Data& Data::operator+=(int day) {
	if (day < 0)
	{
		return *this -= -day;
	}
	_day += day;
	while (_day > GetDay(_year,_month))
	{
		_day -= GetDay(_year, _month);
		_month++;
		if (_month == 13)
		{
			_month = 1;
			_year++;
		}
	}
	return *this;
}

Data Data::operator+(int day) {
	Data a = *this;
	a += day;
	return a;
}
Data& Data::operator-=(int day) {
	if (day < 0)
	{
		return *this += -day;
	}
	_day -= day;
	while (_day <= 0)
	{
		--_month;
		if (_month == 0)
		{
			_month = 12;
			--_year;
		}
		_day += GetDay(_year, _month);
	}
	return *this;
}

Data Data::operator-(int day) {
	Data a = *this;
	a -= day;
	return a;
}
Data& Data::operator++() {
	return *this += 1;
}

Data Data::operator++(int) {
	Data a = *this;
	*this += 1;
	return a;
}

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

Data Data::operator--(int) {
	Data tmp = *this;
	*this -= 1;
	return tmp;
}

int Data::operator-(const Data& d) {
	int day = 0;
	Data max = *this;
	Data min = d;
	int flag = 1;
	if (*this < d)
	{
		max = d;
		min = *this;
		flag = -1;
	}
	while (min != max)
	{
		++min;
		++day;
	}
	return day*flag;
}

ostream& operator<<(ostream& out,Data& d){
	out << d._year << "-" << d._month << "-" << d._day << endl;
	return out;
}

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