使用重载运算符（++，+=，<<等）实现日期类的操作。功能包括：
1）设置日期，如果日期设置不符合实际，则设置为默认日期（1900年1月1日）
2）在日期对象中向日期添加1或者加若干天（加入日期值后根据实际的日期进行月份、年份的变化）
3）重载流插入运算符进行

输入样例：

在这里给出一组输入。例如：

13 38 100

12 31 2009

2 28 2000

输出样例：

在这里给出相应的输出。例如：

d1 is January 1, 1900

d2 is December 31, 2009

d1 += 7 is January 8, 1900

d2 is December 31, 2009

++d2 is January 1, 2010

Testing the prefix increment operator:

d3 is February 28, 2000

++d3 is February 29, 2000

d3 is February 29, 2000

Testing the postfix increment operator:

d3 is February 29, 2000

d3++ is February 29, 2000

d3 is March 1, 2000

日期的输出，其中月份要用名称表示

代码实现：

#include  <string>
#include  <iostream>
using  namespace  std;/*  请在这里填写答案  */
class MyDate{private:int y,m,d;int flag1,flag2,flag3;public:void setDate(int ma,int da,int ya){y = ya;m = ma;d = da;}friend ostream& operator <<(ostream &out,MyDate &date);void flag(){if((y%4==0&&y%100!=0)||y%400==0){		//闰年 flag1=1;}else{flag1=0;}if(m<=7){switch(m%2){						//大月小月 case 0 :flag2 = 0;break;case 1:flag2 = 1;break;}}else{switch(m%2){case 0:flag2 = 1;case 1:flag2 = 0; }}if(m==2)flag3=1;						//二月 else flag3 = 0;}void update(){int brk=0;int cunt=0;while(cunt<15){flag();	if(d>28){if(d==29){if(flag1==0&&flag3==1){			//平年且2月 d-=28;m+=1;}else brk=1;}else if(d==30){if(flag1==1&&flag3==1){			//闰年且2月 d-=29;m+=1;}else brk=1;}else if(d==31){if(flag2==0){					//若为小月 d-=30;m+=1; }else brk=1;}else{								//此时无论如何要进 1d-=31;m+=1;} }else{brk=1;}if(m>12){m-=12;y+=1;}if(brk==1)break;cunt++;}}MyDate& operator+=(int n){this->d+=n;update();return *this;}MyDate& operator++(){d++;update();return *this;}MyDate& operator++(int){MyDate *rs = new MyDate(*this);++d;update();return *rs;}	
};
ostream& operator <<(ostream &out,MyDate &date){string month;if(date.y<1900||date.m<=0||date.m>12||date.d<0||date.d>31){date.y=1900;date.m=1;date.d=1;out<<"January 1, 1900"<<endl;return out;}switch(date.m){case 1:month = "January";break;case 2:month = "February";break;case 3:month = "March";break;case 4:month = "April";break;case 5:month = "May";break;case 6:month = "June";break;case 7:month = "July";break;case 8:month = "Augest";break;case 9:month = "September";break;case 10:month = "October";break;case 11:month = "November";break;case 12:month = "December";break;}out<<month<<" "<<date.d<<","<<date.y<<endl;return out;
}int  main()
{int  m,d,y;MyDate  d1,d2,d3;cin>>m>>d>>y;d1.setDate(m,d,y);cin>>m>>d>>y;d2.setDate(m,d,y);cin>>m>>d>>y;d3.setDate(m,d,y);cout  <<  "d1  is  "  <<  d1  <<  "\nd2  is  "  <<  d2;cout  <<  "\n\nd1  +=  7  is  "  <<  (  d1  +=  7  );cout  <<  "\n\n  d2  is  "  <<  d2;cout  <<  "\n++d2  is  "  <<  ++d2;cout  <<  "\n\nTesting  the  prefix  increment  operator:\n"<<  "  d3  is  "  <<  d3  <<  endl;cout  <<  "++d3  is  "  <<  ++d3  <<  endl;cout  <<  "  d3  is  "  <<  d3;cout  <<  "\n\nTesting  the  postfix  increment  operator:\n"<<  "  d3  is  "  <<  d3  <<  endl;cout  <<  "d3++  is  "  <<  d3++  <<  endl;cout  <<  "  d3  is  "  <<  d3  <<endl;
}