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1. 头文件

#pragma once
#include <iostream>
using namespace std;class Date
{
public:Date(int year = 1, int month = 1, int day = 1);int GetMonthDay();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;Date& operator+=(int day);Date operator+(int day) const;Date& operator-=(int day);Date operator-(int day) const;Date& operator++();Date operator++(int);Date& operator--();Date operator--(int);int operator-(const Date& d) const;friend ostream& operator<<(ostream& _out, const Date& d);friend istream& operator>>(istream& _in, Date& d);void Print() const;private:int _year;int _month;int _day;
};

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2. 主函数的实现

#include "Date.h"Date::Date(int year, int month, int day): _year(year), _month(month), _day(day)
{}int Date::GetMonthDay()
{int day[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 day[2] + 1;}return day[_month];
}bool Date::operator>(const Date & d)const
{if (_year > d._year){return true;}else if (_year == d._year){if (_month > d._month){return true;}else if (_month == d._month){return _day > d._day;}}return false;
}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);
}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);
}Date& Date::operator+=(int day)
{_day += day;while (_day > GetMonthDay()){_day -= GetMonthDay();++_month;if (_month > 12){_month = 1;++_year;}}return *this;
}Date Date::operator+(int day) const
{Date tmp = *this;tmp += day;return tmp;
}Date& Date::operator-=(int day)
{_day -= day;while (_day < 1){--_month;if (_month < 1){_month = 12;--_year;}_day += GetMonthDay();}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) const
{int flag = 1;Date max = *this;Date min = d;if (*this < d){flag = -1;max = d;min = *this;}int n = 0;while (min != max){++min;++n;}return (n * flag);
}void Date::Print() const
{cout << _year << "/" << _month << "/" << _day << endl;
}ostream& operator<<(ostream& _out, const Date& d)
{_out << d._year << "/" << d._month << "/" << d._day;return _out;
}istream& operator>>(istream& _in, Date& d)
{_in >> d._year >> d._month >> d._day;return _in;
}

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3. 目录文件

#include "Date.h"
int main()
{int input = 0;do {cout << "                                **********  欢迎进入日期计算器  ****************" << endl;cout << "                                **********  1.计算两日期差几天  ****************" << endl;cout << "                                **********  2.计算某日往后n天   ****************" << endl;cout << "                                **********  3.计算某日往前n天   ****************" << endl;cout << "                                **********  0.  退出系统       ****************" << endl;printf("\n\n\n");cout << "请选择：";cin >> input;if (input == 1){Date d1;Date d2;cout << "请输入第一个日期：";cin >> d1;cout << "请输入第二个日期：";cin >> d2;cout << d1 << "和" << d2 << "相差" << (d2 - d1) << "天" << endl;printf("\n\n\n");}else if (input == 2){Date d1;int day = 0;cout << "请输入某日日期：";cin >> d1;cout << "请输入往后多少天：";cin >> day;cout << d1 << "往后" << day << "天是" << (d1 + day) << endl;printf("\n\n\n");}else if (input == 3){Date d1;int day = 0;cout << "请输入某日日期：";cin >> d1;cout << "请输入往前多少天：";cin >> day;cout << d1 << "往前" << day << "天是" << (d1 - day) << endl;printf("\n\n\n");}else if (input == 0){break;}else{cout << "请输入正确的选项" << endl;printf("\n\n\n");}} while (input);
}

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有需要自取 gitee 链接  ：日期计算器——有趣的中国人的gitee