C++日期類的實現運算符的重載

今天寫了簡單的C++日期類，有興趣的可以看一下

其聲明Date.h:

#define _CRT_SECURE_NO_WARNINGS 1
#ifndef  __ONCEDATE__
#define  __ONCEDATE__
#include<iostream>
using namespace std;
class Date
{
public:
Date(int year = 1900, int mouth = 1, int day = 1);//構造函數
bool operator == (const Date& d);//日期比較符號的重載
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);//運算符的重載
Date operator+= (int day);
Date operator- (int day);
Date operator-= (int day);
Date operator++();
Date operator++(int);
Date operator--();
Date operator--(int);
void display();//打印函數，野可以重載cout
int operator-(const Date& d);//代碼中沒有實現，有興趣的可以試一下
private:
bool IsLeapYear(int year);//判斷閏年的私有類函數
int GetMonthDay(int year, int month);//獲取月份的私有類函數
int _year;
int _mouth;
int _day;
};
#endif

定義如下：
#include <iostream>
#include "Date.h"
using namespace std;
 void Date  :: display()
{
cout << _year << " " << _mouth << " "
<< _day << endl;
}
 Date::Date(int year , int mouth, int day )
 {
 if ((year >= 0) &&
 (mouth > 0 && mouth<13) &&
 (day>0 && day <= GetMonthDay(year, mouth)))
 {
 _year = year;
 _mouth = mouth;
 _day = day;
 }
 else
 {
 cout << "日期錯誤，改為默認日期" << endl;
 _year = 1900;
 _mouth = 1;
 _day = 1;
 }
 }
bool Date:: operator == (const Date& d)
 {
 return this->_year == d._year
 && this->_mouth == d._mouth
 && this->_day == d._day;
 }
bool Date:: operator <(const Date& d)
{
if (_year < d._year)
return true;
if (_year == d._year)
{
if (_mouth == d._mouth)
{
if (_day == d._day)
{
return false;
}
else if (_day < d._day)
return true;
}
else if (_mouth < d._mouth)
return true;
}
return false;
}
bool Date:: operator <=(const Date& d)
{
if (*this<d || *this == d)
return true;
return false;
}
bool Date:: operator >(const Date& d)
{
if (!(*this <= d))
return true;
return false;
}
bool Date:: operator >=(const Date& d)
{
if (!(*this < d))
return true;
return false;
}
bool Date:: operator !=(const Date& d)
{
return !(*this == d);
}
Date Date:: operator+ (int day)//日期加天數，因為定義的天數為int型，所以可能加一個負的天數
{  //故在循環中添加了判斷處理，若負責執行減操作，反之執行加操作
Date DestDate(*this);
DestDate._day += day;
while (DestDate._day > GetMonthDay(DestDate._year, DestDate._mouth) ||
DestDate._day <= 0)
{
if (DestDate._day>0)
{
DestDate._day -= GetMonthDay(DestDate._year, DestDate._mouth);
if (DestDate._mouth == 12)
{
DestDate._mouth = 0;
DestDate._year++;
}
DestDate._mouth++;
}
else
{
DestDate._day += GetMonthDay(DestDate._year, DestDate._mouth);
if (DestDate._mouth == 1)
{
DestDate._mouth = 13;
DestDate._year--;
}
DestDate._mouth--;
}
}
return DestDate;
}
Date Date:: operator+= (int day)
{
*this = *this + day;
return *this;
}
Date Date:: operator- (int day)
{
day = -day;
return *this + day;
}
Date Date:: operator-= (int day)
{
*this = *this - day;
return *this;
}
Date Date:: operator++()
{
Date DestDate(*this);
*this += 1;
return DestDate;
}
Date Date:: operator++(int)
{
*this += 1;
return *this;
}
Date Date:: operator--()
{
Date Destdate(*this);
--*this;
return Destdate;
}
Date Date:: operator--(int)
{
*this -= 1;
return *this;
}
int Date:: operator-(const Date& d)//日期-日期的實現主要先比較日期的大小，再用計數器
{  //統計小日期加多少天月大日期變為同一日期，最後輸出結果
Date high(d);
Date low;
int count = 0;
int flag = 1;
if (*this > d)
{
low = high;
high = *this;
}
else
{
flag = 0;
low = *this;
}
while (low != high)
{
low++;
count++;
}
if (!flag)
count = -count;
return count;
}
bool Date::IsLeapYear(int year)
{
if (((year % 4 == 0) && (year % 100)) ||
(year % 400 == 0))
{
return true;
}
return false;
}
int Date::GetMonthDay(int year, int month)//用一個數組存儲1-12月所占天數
{
int monthArray[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
int day = monthArray[month];
if (month == 2 && IsLeapYear(year))
{
day += 1;
}
return day;
}

如有不足之處希望批評指正，如有疑惑野可以留言探討