C++之日期类的实现之默认成员函数和运算符重载的综合应用（+、、=、＜、＞、+=、=）

在完成日期类时&＃xff0c;涉及到对应月份天数的限制&＃xff0c;先构造出下面的函数&＃xff0c;用以判断当月天数。

//获取某一月的天数
int Date::GetMonthDay(int year, int month)
{static int daysArray[13] &＃61; { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };int days &＃61; daysArray[month];if (month &＃61;&＃61; 2 && ((year % 4 &＃61;&＃61; 0 && year % 100 !&＃61; 0) || (year % 400 &＃61;&＃61; 0))){days &＃61; 29;}return days;
}


Date.h文件

#pragma once
#include
using namespace std;
class Date
{
public:int GetMonthDay(int year, int month);void Print();Date(int year &＃61; 1900, int month &＃61; 1, int day &＃61; 1);/*拷贝构造函数*/Date(const Date& d);// 赋值运算符重载// d2 &＃61; d3 -> d2.operator&＃61;(&d2, d3)Date& operator&＃61;(const Date& d);// 析构函数~Date();//d1 &＃43;&＃61; 10Date& operator&＃43;&＃61;(int day);//d1 &＃43; 10Date operator&＃43;(int day);//d1 -&＃61; 10Date& operator-&＃61;(int day);//d1 - 10Date operator-(int day);//&＃43;&＃43;d1//d1.operator&＃43;&＃43;(&d1)Date& operator&＃43;&＃43;();//d1&＃43;&＃43;//d1.operator&＃43;&＃43;(&d1&＃xff0c;0)//为了跟前置&＃43;&＃43;区分&＃xff0c;加了一个参数&＃xff0c;但是这个参数不使用Date operator&＃43;&＃43;(int);bool operator>(const Date& d);// &＃61;&＃61;运算符重载bool operator&＃61;&＃61;(const Date& d);// >&＃61;运算符重载inline bool operator >&＃61; (const Date& d);// <运算符重载bool operator < (const Date& d);// <&＃61;运算符重载bool operator <&＃61; (const Date& d);// !&＃61;运算符重载bool operator !&＃61; (const Date& d);// 日期-日期 返回天数int operator-(const Date& d);
private:int _year;int _month;int _day;
};


Date.cpp文件

#include"Date.h"//拷贝构造函数Date::Date(const Date& d)
{_year &＃61; d._year;_month &＃61; d._month;_day &＃61; d._day;
}// 赋值运算符重载// d2 &＃61; d3 -> d2.operator&＃61;(&d2, d3)Date& Date::operator&＃61;(const Date& d){if (this !&＃61; &d){_year &＃61; d._year;_month &＃61; d._month;_day &＃61; d._day;}return *this;}// 析构函数Date:: ~Date(){// 清理工作&＃xff0c;Date类中没有需要清理的资源// 所以严格来说Date不需要写析构函数&＃xff0c;因为我们不写&＃xff0c;编译器默认生成就可以用cout << "~Date()" << endl;}//打印函数
void Date::Print()
{cout << _year << "-" << _month << "-" << _day << endl;
}//获取某一月的天数
int Date::GetMonthDay(int year, int month)
{static int daysArray[13] &＃61; { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };int days &＃61; daysArray[month];if (month &＃61;&＃61; 2 && ((year % 4 &＃61;&＃61; 0 && year % 100 !&＃61; 0) || (year % 400 &＃61;&＃61; 0))){days &＃61; 29;}return days;
}
//判断日期是否非法Date::Date(int year, int month, int day)
{_year &＃61; year;_month &＃61; month;_day &＃61; day;//cout <<"Date(int year,int month,int day)" <if (!(year >&＃61; 0 && month > 0 && month < 13 && day > 0 && day < GetMonthDay( year, month))){cout << "日期非法" << endl;}}//d1 &＃43;&＃61; 10Date& Date::operator &＃43;&＃61; (int day)//赋值运算符重载的特点{if (day < 0){return *this -&＃61; -day;}_day &＃43;&＃61; day;//日期是否合法while (_day > GetMonthDay(_year, _month)){_day -&＃61; GetMonthDay(_year, _month);_month&＃43;&＃43;;if (_month &＃61;&＃61; 13){_year&＃43;&＃43;;_month &＃61; 1;}}return *this;}//d1 &＃43; 10//要实现&＃43;&＃xff0c;d1的值是不能被改变的&＃xff0c;所以拷贝构造一个ret//ret为&＃43;后的结果Date Date::operator&＃43;(int day){//Date ret(*this);//拷贝构造//ret._day &＃43;&＃61; day;//while (ret._day > GetMonthDay(ret._year, ret._month))//{// ret._day -&＃61; GetMonthDay(ret._year, ret._month);// ret._month&＃43;&＃43;;// if (ret._month &＃61;&＃61; 13)// {// ret._year&＃43;&＃43;;// ret._month &＃61; 1;// }//}Date ret(*this);ret &＃43;&＃61; day;//直接调用&＃43;&＃61;&＃xff0c;ret.operator(day)return ret;}//d1-&＃61;dayDate& Date::operator-&＃61;(int day){if (day < 0){return *this &＃43;&＃61; -day;}//日期是否合法_day -&＃61; day;while (_day < 0){_day &＃43;&＃61; GetMonthDay(_year, _month);_month--;if (_month &＃61;&＃61; 0){_year--;_month &＃61; 1;}}return *this;}//d1-dayDate Date::operator-(int day){Date ret(*this);ret -&＃61; day;return ret;}//&＃43;&＃43;d1 等价于 d1 &＃43;&＃61; 1Date& Date::operator&＃43;&＃43;(){*this &＃43;&＃61; 1;//直接return *this;}//d1&＃43;&＃43;Date Date::operator&＃43;&＃43;(int){Date ret(*this);//要返回&＃43;&＃43;之前的值&＃xff0c;所以先拷贝构造一个保存起来*this &＃43;&＃61; 1;return ret;//出了作用域就不存在了&＃xff0c;不能用引用返回}// &＃61;&＃61;运算符重载bool Date :: operator&＃61;&＃61;(const Date& d){return _year &＃61;&＃61; d._year && _month &＃61;&＃61; d._month && _day &＃61;&＃61; d._day;}bool Date::operator>(const Date& d){if (_year > d._year){return true;}else if (_year &＃61;&＃61; d._year){if (_month > d._month){return true;}else if (_month &＃61;&＃61; d._month){if (_day > d._day){return true;}}}return false;}// >&＃61;运算符重载bool Date::operator >&＃61; (const Date& d){return (*this > d) || (*this &＃61;&＃61; d);}// <运算符重载bool Date::operator < (const Date& d){return !(*this >&＃61; d);}// <&＃61;运算符重载bool Date::operator <&＃61; (const Date& d){return !(*this > d);}// !&＃61;运算符重载bool Date::operator !&＃61; (const Date& d){return !(*this &＃61;&＃61; d);}// 日期-日期 返回天数int Date::operator-(const Date& d)//函数名相同&＃xff0c;参数不同&＃xff0c;构成重载{//直接进行日期之间的相减很难Date max &＃61; *this, min &＃61; d;int flag &＃61; 1;if (*this < d){max &＃61; d;min &＃61; *this;flag &＃61; -1;}int n &＃61; 0;while (min !&＃61; max)//n 的数就是相差的天数{&＃43;&＃43;n;&＃43;&＃43;min;}return n*flag;}