日期类

#include<iostream>
#include<assert.h>
using namespace std;

class Date
{
public:
void Display()
{
cout << _year << "-" << _month << "-" << _day << endl;
}
public:
Date(int year, int month, int day)
{//应判断日期是否有效
//cout << "Date(int year, int month, int day)" << endl;
if (year >= 2000 && month > 0 && month<13 && day>0 && day <= GetMonthDay(year, month))
{
_year = year;
_month = month;
_day = day;
}
else
{
cout << "日期非法！" << endl;
assert(false);
}
}
Date (const Date& d)
{
//cout << "Date (const Date& d)" << endl;
this->_year = d._year;
this->_month = d._month;
this->_day = d._day;
}
~Date()
{
//cout << "~Date()" << endl;
}
public://两个日期相比较
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);
public://日期计算器
Date operator +(int day);
Date& operator +=(int day);
Date operator -(int day);
Date& operator -=(int day);
Date& operator++();//前置++
Date operator++(int);//后置++
Date& operator--();//前置--
Date operator--(int);//后置--
int GetMonthDay(int year, int month);
int operator -(const Date& d);//两个日期间相差的天数
private:
int _year;
int _month;
int _day;
};

bool Date::operator == (const Date& d)
{
return this->_year == d._year&&this->_month == d._month&&this->_day == d._day;
}
bool Date::operator < (const Date& d)
{
return this->_year < d._year ||
(this->_year == d._year&&this->_month < d._month) ||
(this->_year == d._year&&this->_month == d._month&&this->_day < d._day);
}
bool Date::operator <= (const Date& d)
{//复用代码
return *this<d || *this == d;
}
bool Date::operator > (const Date& d)
{
return this->_year > d._year ||
(this->_year == d._year&&this->_month > d._month) ||
(this->_year == d._year&&this->_month == d._month&&this->_day > d._day);
}
bool Date::operator >= (const Date& d)
{//复用代码
return *this>d || *this == d;
}

//日期计算器
int Date::GetMonthDay(const int year, const int month)//获得具体某年某月的总天数
{
int day;
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
day = 31;
else if (month == 2)
{
if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
day = 29;
else
day = 28;
}
else
day = 30;
return day;
}

Date Date::operator +(int day)//日期加天数
{
if (day < 0)
return *this - (-day);
Date tmp = *this;
tmp._day += day;
while (tmp._day >(GetMonthDay(tmp._year, tmp._month)))
{
tmp._day -= GetMonthDay(tmp._year, tmp._month);
if (tmp._month == 12)
{
tmp._year += 1;
tmp._month = 1;
}
else
tmp._month += 1;
}
return tmp;
}
Date& Date::operator +=(const int day)
{
return *this = *this + day;
}
Date Date::operator -(const int day)//日期减天数
{
if (day < 0)
return *this + (-day);
Date tmp = *this;
tmp._day -= day;
while (tmp._day <= 0)
{
if (tmp._month == 1)
{
--tmp._year;
tmp._month = 12;
}
else
tmp._month--;
tmp._day += GetMonthDay(tmp._year, tmp._month);
}
return tmp;
}
Date& Date::operator -=(const int day)
{
return *this = *this - day;
}
Date& Date::operator++()//前置++
{
*this += 1;
return *this;
}
Date Date::operator++(int)//后置++
{
Date tmp = *this;
*this += 1;
return tmp;
}
Date& Date::operator--()//前置--
{
*this -= 1;
return *this;
}
Date Date::operator--(int)//后置--
{
Date tmp = *this;
*this -= 1;
return tmp;
}

int Date::operator -(const Date& d)//两个日期间相差的天数
{//通过较小的日期不断自加，直到等于较大的日期，统计出自加次数
int flag = 1;
int days = 0;
Date max = *this;
Date min = d;
if (max < min)
{//调用C++库函数中的swap（std::swap()）
std::swap(max._year, min._year);
std::swap(max._month, min._month);
std::swap(max._day, min._day);
flag = -1;
}
while(!(min == max))
{
min++;
days++;
}
return flag*days;
}
void Test1()
{//比较日期大小
Date p1(2016, 1, 20);
Date p2(2016, 1, 25);
p1.Display();
p2.Display();
bool ret;
ret = p1 == p2;
cout << "---------ret = " << ret << endl;
ret = p1 > p2;
cout << "---------ret = " << ret << endl;
ret = p1 < p2;
cout << "---------ret = " << ret << endl;
}

void Test2()
{//日期加减天数
Date p1(2016, 2, 20);
Date p2(2016, 1, 25);
p1.Display();
p1 = p1 + 41;
p1.Display();
cout << endl;
++p1;
p1.Display();
p1++;
p1.Display();
cout << endl;
p2.Display();
p2 = p2 - 56;
p2.Display();
cout << endl;
--p2;
p2.Display();
p2--;
p2.Display();
}

void Test3()
{//两个日期间相差的天数
Date p1(2016, 2, 20);
Date p2(2016, 1, 25);
int days = p1 - p2;
cout << days << endl;
}

int main()
{
Test1();
Test2();
Test3();
system("pause");
return 0;
}