第八周（运算符重载）Time类

/*

*copyright(c) 2015,烟台大学计算机学院

*All rights reserved。

*文件名称：第八周（运算符重载）

*作者：王忠

*完成日期：2015.4.28

*版本号：v1.0

*

*问题描述：实现Time类中的运算符重载。

*输入描述：

*程序输出：

#include <iostream>

using namespace std;

class CTime
{
private:
    unsigned short int hour;    // 时
    unsigned short int minute;  // 分
    unsigned short int second;  // 秒
public:
    CTime(int h=0,int m=0,int s=0)
    {
        hour=h;
        minute=m;
        second=s;
    }
    void setTime(int h,int m,int s)
    {
        hour=h;
        minute=m;
        second=s;
    }
    void display()
    {
        cout<<hour<<":"<<minute<<":"<<second<<endl;
    }
    //二目的比较运算符重载
    bool operator > (CTime &t);
    bool operator < (CTime &t);
    bool operator >= (CTime &t);
    bool operator <= (CTime &t);
    bool operator == (CTime &t);
    bool operator != (CTime &t);
    //二目的加减运算符的重载
    //返回t规定的时、分、秒后的时间
    //例t1(8,20,25),t2(11,20,50)，t1+t2为19:41:15
    CTime operator+(CTime &t);
    CTime operator-(CTime &t);//对照+理解
    CTime operator+(int s);//返回s秒后的时间
    CTime operator-(int s);//返回s秒前的时间
    //二目赋值运算符的重载
    CTime operator+=(CTime &c);
    CTime operator-=(CTime &c);
    CTime operator+=(int s);//返回s秒后的时间
    CTime operator-=(int s);//返回s秒前的时间
};
bool CTime::operator > (CTime &t)
{
    if(hour>t.hour) return true;
    if(hour<t.hour) return false;
    if(minute>t.minute) return true;
    if(minute<t.minute) return false;
    if(second>t.second) return true;
    return false;
}
bool CTime::operator < (CTime &t)
{
    if(hour<t.hour) return true;
    if(hour>t.hour) return false;
    if(minute<t.minute) return true;
    if(minute>t.minute) return false;
    if(second<t.second) return true;
    return false;
}
bool CTime::operator >= (CTime &t)
{
    if(*this<t)return false;
    return true;
}
bool CTime::operator <= (CTime &t)
{
    if(*this>t)return false;
    return true;
}
bool CTime::operator == (CTime &t)
{
    if(*this>t||*this<t) return false;
    return true;
}
bool CTime::operator != (CTime &t)
{
    if(*this==t) return false;
    return true;
}
CTime CTime::operator+(CTime &t)
{
    hour=hour+t.hour;
    minute=minute+t.minute;
    second=second+t.second;
    if(second>59)
    {
        minute++;
        second=second%60;
    }
    if(minute>59)
    {
        hour++;
        minute=minute%60;
    }
    if(hour>23)
        hour=hour%24;
    CTime t2(hour,minute,second);
    return t2;
}
CTime CTime::operator-(CTime &t)
{
    hour=hour-t.hour;
    minute=minute-t.minute;
    second=second-t.second;
    if(second<0)
    {
        minute--;
        second=second+60;
    }
    if(minute<0)
    {
        hour--;
        minute=minute+60;
    }
    if(hour<0)
        hour=hour+24;
    CTime t2(hour,minute,second);
    return t2;
}
CTime CTime::operator+(int s)//返回s秒后的时间
{
    second=second+s;
    int ss=s/60;
    if(second>59)
    {
        minute+=ss;
        second=second%60;
    }
    int mm=minute/60;
    if(minute>59)
    {
        hour+=mm;
        minute=minute%60;
    }
    if(hour>23)
        hour=hour%24;
    CTime t2(hour,minute,second);
    return t2;
}
CTime CTime::operator-(int s)//返回s秒前的时间
{
    second=second-s;
    if(second<0)
    {
        minute--;
        second=second+60;
    }
    if(minute<0)
    {
        hour--;
        minute=minute+60;
    }
    if(hour<0)
        hour=hour+24;
    CTime t2(hour,minute,second);
    return t2;
}
CTime CTime::operator+=(CTime &c)
{
    *this=*this+c;
    return *this;
}
CTime CTime::operator-=(CTime &c)
{
    *this=*this-c;
    return *this;
}
CTime CTime::operator+=(int s)//返回s秒后的时间
{
    *this=*this+s;
    return *this;
}
CTime CTime::operator-=(int s)//返回s秒前的时间
{
    *this=*this-s;
    return *this;
}
int main()
{
    CTime t1(8,20,25),t2(11,20,50),t;
    cout<<"t1为：";
    t1.display();
    cout<<"t2为：";
    t2.display();
    cout<<"下面比较两个时间大小：\n";
    if (t1>t2) cout<<"t1>t2"<<endl;
    if (t1<t2) cout<<"t1<t2"<<endl;
    if (t1==t2) cout<<"t1＝t2"<<endl;
    if (t1!=t2) cout<<"t1≠t2"<<endl;
    if (t1>=t2) cout<<"t1≥t2"<<endl;
    if (t1<=t2) cout<<"t1≤t2"<<endl;
    cout<<endl;
    //在测试下面的代码时，请采用单步执行的方法跟踪
    t=t1+t2;
    t.display();
    t=t1-t2;
    t=t1+2000;
    t.display();
    t=t1-5000;
    t1+=t2;
    t1-=t2;
    t1+=2000;
    t1-=5000;
    return 0;
}

太弱了，测试函数写不出来，测试不全。在CTime CTime::operator+(CTime &t)这里时总是输出一个随机数，怎么看怎么写的对，就是不输出正确答案，最后发现没返回一个对象