c++日期类的实现

#define _CRT_SECURE_NO_WARNINGS#include <iostream>#include <assert.h>using namespace std;class Date{public://构造函数Date(int year = 1995, int month = 2, int day = 12):_year(year), _month(month), _day(day){if (IsInvalid())       //判断日期合法性{_year = year;_month = month;_day = day;}}//检验日期的合法性bool IsInvalid(){if (_year > 0 && _month > 0 && _month<13 && _day>0 && _day <= GetMonthDay(_year, _month)){return true;}else{return false;}}//检测本年份是否为闰年bool IsLaerYear(int year){if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)){return true;}elsereturn false;}//获得某个月份的天数int GetMonthDay(int year, int month){int day = 0;if (month > 0 && month < 13){static int days[] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };day = days[month];if (month == 2 && IsLaerYear(year)){day = 29;            //闰年2月29天}}return day;}//拷贝构造函数Date(const Date& d1){_year = d1._year;_month = d1._month;_day = d1._day;}//赋值运算符的重载Date& operator=(const Date& d){if (_year == d._year){if (_month == d._month){if (_day == d._day){return *this;}}}}//X天之后的日期Date operator+(int days)  //10000{Date tmp = *this;int MonthDay = 0;while (tmp._day += days){MonthDay = GetMonthDay(tmp._year, tmp._month);if (tmp._day <= MonthDay){break;}days = tmp._day - MonthDay;tmp._month++;tmp._day = 0;if (tmp._month == 12){tmp._year++;tmp._month = 1;}}return tmp;}//X天之前的日期Date operator-(int days){Date tmp = *this;int MonthDay = 0;if (tmp._day == days){tmp._month--;if (tmp._month < 1){tmp._month = 12;tmp._year--;}tmp._day = GetMonthDay(tmp._year, tmp._month);days = 0;}if (tmp._day > days){tmp._day -= days;return tmp;}days -= tmp._day;tmp._month--;if (tmp._month < 1){tmp._month = 12;tmp._year--;}MonthDay = GetMonthDay(tmp._year, tmp._month);while (days){if(days < MonthDay){tmp._day = MonthDay - days;days = 0; break;}else{days -= MonthDay;tmp._month--;if (tmp._month < 1){tmp._month = 12;tmp._year--;}MonthDay = GetMonthDay(tmp._year, tmp._month);}}return tmp;}//X天之前的日期的优化//Date operator -(int day)//{//Date tmp = *this;//while (day >= tmp._day)//{//tmp._month--;//day -= tmp._day;//if (day == tmp._day)//{//day = 0;//}//if (tmp._month < 1)//{//tmp._year--;//tmp._month = 12;//}//tmp._day = GetMonthDay(tmp._year, tmp._month);//}//tmp._day -= day;//return tmp;//}//两个日期相减的到的天数，即两个日期中间相隔多少天int  operator-(const Date& d){int day = 0;int MonthDay = 0;while ((_year != d._year) || (_month != d._month) || (_day != d._day)){day += _day;_month--;if (_month < 1){_month = 12;_year--;}_day = GetMonthDay(_year, _month);if ((_year == d._year) && (_month == d._month) && (_day !=d._day)){day += GetMonthDay(_year, _month) - d._day;_day = d._day;}}return day;}//天数的前置加加Date& operator++(){_day++;if (_day > GetMonthDay(_year, _month)){_month++;_day = 1;if (_month > 12){_year++;_month = 1;}}return *this;}//天数的后置加加Date operator++(int){Date tmp = *this;_day++;if (tmp._day > GetMonthDay(tmp._year, tmp._month)){tmp._month++;tmp._day = 1;if (tmp._month > 12){tmp._year++;tmp._month = 1;}}return tmp;}//天数的前置减减Date& operator--(){_day--;if (_day < 1){_month--;if (_month < 1){_year--;_month = 12;}_day = GetMonthDay(_year, _month);}return *this;}//天数的后置减减Date operator--(int){Date tmp = *this;_day--;if (tmp._day < 1){tmp._month--;if (tmp._month < 1){tmp._year--;tmp._month = 12;}tmp._day = GetMonthDay(tmp._year, tmp._month);}return tmp;}//输出运算的重载声明friend ostream& operator<<(ostream& _cout, const Date& d);private:int _year;int _month;int _day;};//输出运算的重载定义ostream& operator<<(ostream& os, const Date& d){os << d._year << "-" << d._month << "-" << d._day;return os;}int main(){Date d1(1970, 5, 14);Date d2(1970, 11, 4);Date d3(1995, 2, 11);//cout << d1 + 100 << endl;//cout << d1 - 11 << endl;cout << "d1 = " << d1 << endl;cout << "d2 = " << d2 << endl;cout << "d3 = " << d3 << endl;cout << "d2 - d1 = " << d2 - d1 << endl;//cout << "--d3 =" << --d3 << endl;//cout << "d3-- =" << d3-- << endl;//cout << "++d3 =" << ++d3 << endl;cout << "d3++ =" << d3++ << endl;system("pause");return 0;}