设计一个日期类Date,，要求： （1）包含年(year)、月(month)和日(day)私有数据成员。 （2）包含构造函数，重载关于一日期加上天数的加法运算符+、重载关于一日期减去天数的减加运算符-

#include

class Date{
private:
	double year,month,day;
public:
	Date(double y=0,double m=0,double d=0):year(y),month(m),day(d){};
	Date operator+(Date b);                         //重载运算符+
	Date operator-(Date b);                         //重载运算符-
	friend ostream &operator<<(ostream &os,Date &s);//重载流运算符<<
	friend istream &operator>>(istream &is,Date &s);//重载流运算符>>
	void Show();
};
Date Date::operator+(Date b){
    if((day+b.day)>31){
	   month++;
	   int dd=day+b.day-31;
	return Date(year,month,dd);
	   }
	else
	return Date(year,month,day+b.day);
	
}
Date Date::operator-(Date b){
	if(day-b.day<=0){
		month--;
		int dd=day-b.day+30;
	return Date(year,month,dd);
	}
		else
	return Date(year,month,day-b.day);
}
void Date::Show(){
	cout<>(istream &is,Date &s){
	cout<<"按顺序输入年 月 日"<>s.year;
	is>>s.month;
	is>>s.day;
	cout<>t1;
	cout<