C++下的Date类编写

Date类的编写要求如下，编写构造函数以及运算符的重载，以及测试基础代码

class Date

{                                      
public:
Date(int year = 1900, int month = 1, int day = 1)
:_year(year)
,_month(month)
,_day(day)
{
// 如何检查一个日期是否合法
int days = GetMonthDays(year, month);
if (days == -1 || day < 1 || day > days)
{
cout<<"日期不合法"<<endl;
Display();
exit(-1);
}
}

//d1 > d2
bool operator>(const Date& d);
//operator>=
//operator<
//operator<=
//operator==
//operator!=

//d1 + 100
Date operator+(int day);
Date operator+=(int day);
Date operator-(int day);
Date operator-=(int day);
Date operator++();
Date operator++(int);
Date operator--();
Date operator--(int);
int operator-(const Date& d);

bool IsLeapYear(int year);
// if /switch/array
int GetMonthDays(int year, int month)；
private:
int _year;
int _month;
int _day;

};                    

代码如下：这份代码的两个日期相减部分在最后做了优化，第一次代码太过于繁琐，可以使用代码复用进行优化。

#define _CRT_SECURE_NO_WARNINGS 1#include<iostream>using namespace std;class Date{public:Date(int year = 1900, int month = 1, int day = 1):_year(year), _month(month), _day(day){// 如何检查一个日期是否合法 int days = GetMonthDays(year, month);if (days == -1 || day < 1 || day > days){cout << "日期不合法" << endl;this->Display();//exit(-1);}}void Display()const{cout << _year << "-" << _month << "-" << _day << endl;}//d1 > d2 bool operator>(const Date& d)                //>{if (this->_year > d._year){return true;}else if (this->_year == d._year){if (this->_month > d._month){return true;}else if (this->_month == d._month){if (this->_day > d._day){return true;}}}return false;}static bool IsLeapYear(int year){if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)){return true;}return false;}inline static int GetMonthDays(int year, int month){if (year < 1900 || month<1 || month>12){return -1;}static int arr[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };int days = arr[month];if ((month == 2) && (IsLeapYear(year))){days += 1;}return days;}//operator>= bool operator >=(const Date& d)              //>={return (*this>d)||(*this==d);}//operator< bool operator<(const Date& d)                //<{return !(*this>= d);}//operator<= bool operator<=(const Date& d)              //<={return (*this < d || *this == d);}//operator== bool operator==(const Date& d)              //=={return _year == d._year&& _month == d._month&& _day == d._day;}//operator!= bool operator!=(const Date& d)              //!={return !(*this == d);}bool IsInvalid(){if (_year < 1900 || _month<1 || _month>12 || _day<1 || _day>GetMonthDays(_year, _month)){return true;}else{return false;}}//d1 + 100 Date operator+(int day)                        //+{if (day < 0){return *this - (-day);}Date tmp(*this);tmp._day += day;while (tmp.IsInvalid()){tmp._day -= GetMonthDays(tmp._year, tmp._month);tmp._month++;if (tmp._month == 13){tmp._year++;tmp._month = 1;}}return tmp;}Date operator+=(int day)                     //+={if (day < 0){return *this -= (-day);}_day += day;while (IsInvalid()){_day -= GetMonthDays(_year, _month);_month++;if (_month == 13){_year++;_month = 1;}}return *this;}Date operator-(int day)                //-{if (day < 0){return *this + (-day);}Date tmp(*this);tmp._day -= day;while (tmp.IsInvalid()==true){if (tmp._month == 1){tmp._year--;tmp._month = 12;}else{tmp._month--;}tmp._day += tmp.GetMonthDays(tmp._year, tmp._month);}return tmp;}Date operator-=(int day)             //-={if (day < 0){return *this += (-day);}_day -= day;while (IsInvalid() == true){if (_month == 1){_year--;_month = 12;}else{_month--;}_day += GetMonthDays(_year, _month);}return *this;}Date operator++()          //前置++{*this+=1;return *this;}Date operator++(int)          //后置++{Date tmp(*this);*this+=1;return tmp;}Date operator--()               //前置--{*this -= 1;return *this;}Date operator--(int)             //后置--{Date tmp(*this);*this -= 1;return tmp;}int operator-(const Date& d)        //一个日期减去一个日期，相差多少天{                                   //将两个日期分别与初始定义的1900-1-1相减，得到两个天数再相减int Leapyearday = 366;int Noleapyearday = 365;Date chushi;Date tmp1(*this);int day1 = tmp1._day ;while (tmp1._month >chushi._month){tmp1._month--;day1 += tmp1.GetMonthDays(tmp1._year, tmp1._month);}while (tmp1._year >chushi._year){tmp1._year--;if (tmp1.IsLeapYear(tmp1._year)){day1 += Leapyearday;}else{day1 += Noleapyearday;}}Date tmp2(d);int day2 = tmp2._day;while (tmp2._month >chushi._month){tmp2._month--;day2 += tmp2.GetMonthDays(tmp2._year, tmp2._month);}while (tmp2._year > chushi._year){tmp2._year--;if (tmp2.IsLeapYear(tmp2._year)){day2 += Leapyearday;}else{day2 += Noleapyearday;}}int day = day1 - day2;return day;}private:int _year;int _month;int _day;};

测试用例：

void test(){Date d1;Date d2(1996, 7, 1);d1.Display();d2.Display();cout << d1.operator==(d2)<< endl;cout << d1.operator<=(d2) << endl;cout << d1.operator>=(d2) << endl;cout << d1.operator!=(d2) << endl;cout << d1.operator<(d2) << endl;cout << d1.operator>(d2) << endl;}void test1(){Date d1(1996, 8, 6);Date d3 = ++d1;d3.Display();d3 = d1++;d3.Display();d1.Display();d3 = d1 + 1000;d3.Display();d1 += 1000;d1.Display();}void test2(){Date d1(1996, 8, 6);Date d3 = d1 - 1000;d3.Display();d1.Display();d1 -= 1000;d1.Display();}void test3(){Date d1(1996,8,6);d1.Display();Date d3 = d1--;d3.Display();d1.Display();d3 = --d1;d3.Display();d1.Display();}void test4(){Date d1(1996, 8, 6);Date d2(1994, 7, 1);int days = d2 - d1;cout << days << endl;}

从test（）到test4（）运行结果：

两个日期相减的代码优化：

int operator-(const Date& d)        //一个日期减去一个日期，相差多少天{                                   //比较两个日期的大小，让小的日期做前置++运算，每次增加一天，直到和大的日期相等

                Date min = d;               //增加的天数，就是相差的天数Date max = *this;int flags = 1;          //flags是标志位，大日期减小日期天数为正，反之为负int count = 0;if (*this < d){min = *this;max = d;flags = -1;}while (min != max){++min;++count;}return count*flags;}