程序清单11.4，11.5，11.6——课本313，314页，添加加法运算符

mytime1.h

#ifndef MTTIME0_H
#define MYTIME0_H

class Time
{
private:
int hours;
int minutes;

public:
Time();
Time(int h,int m=0);
void AddMin(int m);
void AddHr(int h);
void Reset(int h=0,int m=0);
Time operator+(const Time & t) const;
void Show() const;
};
#endif

mytime1.cpp

#include<iostream>
#include"mytime1.h"
using namespace std;
Time::Time()
{
hours=minutes=0;
}

Time::Time(int h,int m)
{
hours=h;
minutes=m;
}

void Time::AddMin(int m)
{
minutes+=m;
hours+=minutes/60;
minutes%=60;
}

void Time::AddHr(int h)
{
hours+=h;
}

void Time::Reset(int h,int m)
{
hours=h;
minutes=m;
}

Time Time::operator+(const Time & t) const
{
Time sum;
sum.minutes=minutes+t.minutes;
sum.hours=hours+t.hours+sum.minutes/60;
sum.minutes%=60;
return sum;
}
void Time::Show() const
{
cout<<hours<<" hours，"<<minutes<<" minutes";
}

usetime1.cpp

#include<iostream>
#include"mytime1.h"
int main()
{
using namespace std;
Time planning;
Time coding(2,40);
Time fixing(5,55);
Time total;

cout<<"planning time = ";
planning.Show();
cout<<endl;

cout<<"coding time = ";
coding.Show();
cout<<endl;

cout<<"fixing time = ";
fixing.Show();
cout<<endl;

total=coding+fixing;
cout<<"coding+fixing = ";
total.Show();
cout<<endl;

Time morefixing(3,28);
cout<<"more fixing time = ";
morefixing.Show();
cout<<endl;
total=morefixing.operator+(total);

cout<<"morefixing.operator+(total) = ";
total.Show();
cout<<endl;

system("pause");
return 0;
}