设计一个时间类Time，要求：
（1）包含时(hour)、分(minute)和秒(second)私有数据成员。
（2）包含构造函数，重载关于一时间加上另一时间的加法运算符+、重载关于一时间减去另一时间的减加运算符-、重载输出运算符<<与输入运算符>>等。
源代码如下：
#include<iostream>
using namespace std;
class Time
{
friend istream & operator>>(istream &in,Time &t);
friend ostream & operator<<(ostream & out,Time&t);
private:
int hour;
int minute;
int second;
int day;
public:
Time();
Time(int h,int m,int s);
Time operator+(Time &t);
Time operator-(Time &t);
Time operator>>(Time &t);
Time operator<<(Time &t);
};
Time::Time()
{
hour=0;
minute=0;
second=0;
}
Time::Time(int h,int m,int s)
{
hour=h;
minute=m;
second=s;
if(hour>=24){
day=hour/24;
cout<<"时间为"<<day<<"天之后的"<<endl;
hour=hour%24;}
if(hour<0)
{
cout<<"输入时间错误，无法相减"<<endl;
}
if(minute>=60)
hour=hour+1;
minute=minute%60;
if(minute<0){
hour=hour-1;
minute=minute+60;}
if(second<0){
minute=minute-1;
second=second+60;}
if(second>=60)
minute=minute+1;
second=second%60;
}
Time Time::operator+(Time &t)
{
return Time(hour+t.hour,minute+t.minute,second+t.second);
}
Time Time::operator-(Time &t)
{
return Time(hour-t.hour,minute-t.minute,second-t.second);
}
istream & operator>>(istream &in,Time &t)
{
int h,m,s;
cout<<"请输入时间:"<<endl;
cout<<"请分别输入时、分、秒:"<<endl;
cin>>h>>m>>s;
t.hour=h;
t.minute=m;
t.second=s;
return in;
}
ostream & operator<<(ostream & out,Time&t)
{
cout<<t.hour<<':'<<t.minute<<':'<<t.second<<endl;
return out;
}
main()
{
Time t1;
Time t2;
Time t3;
cin>>t1>>t2;
cout<<"两时间相加："<<endl;
t3=t1+t2;
cout<<t3;
cout<<"两时间相减："<<endl;
t3=t1-t2;
cout<<t3;
return 0;
//This code was written by gfh in SCMZU.
}
运行结果：
