日期类

//万年历
#include<iostream>
using namespace std;

class Date
{
public:
//打印日期
void Display()
{
cout<<"Year:"<<_year<<endl;
cout<<"Month:"<<_month<<endl;
cout<<"Day:"<<_day<<endl;
}

// 初始化列表进行初始化。
Date (int year = 1900, int month = 1, int day = 1)
:_year(year)
,_month(month)
,_day(day)
{
if((year < 1900)
|| (month < 1 || month > 12)
|| (day < 1)||day > GetMonthDay(_year,_month))
cout<<"Input Error"<<endl;
else
;
}

Date (const Date& d)
:_year(d._year)
,_month(d._month)
,_day(d._day)
{}

Date& operator = (const Date& d)
{
if(this != &d)
{
_year = d._year;
_month = d._month;
_day = d._day;
}
return *this;
}

public:
//
// 比较日期的运算符重载
//
bool operator == (const Date& d)//为什么可以折磨写
{
return (_year == d._year
&& _month == d._month
&& _day == d._day);
}
bool operator != (const Date& d)
{
return !(*this == d);
}

bool operator > (const Date& d)//else if
{
if(_year > d._year)
{
return true;
}
if (_year == d._year )
{
if (_month >d._month )
{
return true;
}
if(_month == d._month )
{
if(_day > d._day )
{
return true;
}
}
}
return false;
}
bool operator >= (const Date& d)
{
return *this > d || *this == d;
}
bool operator < (const Date& d)
{
return !(*this >= d);
}
bool operator <= (const Date& d)
{
return !(*this > d);
}

//
// 计算一个日期加减一个天数以后的日期。
//
Date operator+(int day)
{
Date tmp(*this);
tmp._day += day;
while(tmp._day < 0)
{
tmp._day -= GetMonthDay(tmp._year ,tmp._month );
if(tmp._month == 1)
{
tmp._year --;
tmp._month = 12;
}
else
tmp._month --;
return tmp;

}

while(tmp._day > GetMonthDay(tmp._year ,tmp._month ))
{
tmp._day -= GetMonthDay(tmp._year ,tmp._month );
if(tmp._month == 12)
{
tmp._year ++;
tmp._month = 1;
}
else
tmp._month++;
}
return tmp;
}
Date operator-(int day)
{
Date tmp(-day);
return tmp;
}
Date& operator-=(int day)
{
Date *this(-day);
}
Date& operator+=(int day)
{
Date *this(day);
}

const Date& operator++()	// 前置++
{
*this += 1;
return *this;
}
Date operator++(int)		// 后置++
{
Date tmp(*this);
*this += 1;
return tmp;
}
const Date& operator--()	// 前置--
{
*this -= 1;
return *this;
}
Date operator--(int)		// 后置--
{
Date tmp(*this);
*this -= 1;
return tmp;
}

bool IsLeapYear(int year)
{
if((year % 4 == 0 && year % 100 != 0)||(year % 400 == 0))
{
return true;
}
else
return false;
}

int GetMonthDay(int year,int month)
{
static int DayTab[13]= {0,31,28,31,30,31,30,31,31,30,31,30,31};
if(IsLeapYear(year))
DayTab[2] = 29;
else
DayTab[2] = 28;
return DayTab[month];
}
friend istream& operator >>(istream& is,const Date& d);
friend ostream& operator <<(ostream& os,const Date& d);

//
// 两个日期相加没有意义
// 计算两个日期相减以后的差的天数
//

int operator-(const Date& d)
{
int flag = 0;
Date x1 = *this,x2 = d;
if(x1 < x2)
{
flag = -1;
x1 = d;
x2 = *this;
}
int count = 0;
while(x1 == x2)
{
++x2;
count++;
}
return count*flag;
}
private:
int _year;
int _month;
int _day;
};

ostream& operator <<(ostream& os,const Date& d)
{
os<<d._year<<"-"<<d._month<<"_"<<d._day<<endl;
return os;
}
istream& operator >>(istream& is,const Date& d)
{
is>>d._year>>"-">>d._month>>"_">>d._day>>endl;
return is;
}

void TestDate()
{}

int main()
{
Date d1(2008,10,26);
/*cout<<(++d1)<<endl;*/
/*cout<<(d1 + 1)<<endl;*/
/*Date d2(2008,10,27);*/
//cout<<"d1 == d2?  "<<(d1 == d2)<<endl;
//cout<<"d1 != d2?  "<<(d1 != d2)<<endl;
//cout<<"d1 > d2?  "<<(d1 > d2)<<endl;
//cout<<"d1 >= d2?  "<<(d1 >= d2)<<endl;
//cout<<"d1 < d2?  "<<(d1 < d2)<<endl;
//cout<<"d1 <= d2?  "<<(d1 <= d2)<<endl;
/*d2.Display();
Date d3;
d3 = d2;
d3.Display();*/

return 0;
}