第八周任务二：实现Time 类中的运算符重载

* (程序头部注释开始)
* 程序的版权和版本声明部分
* Copyright (c) 2011, 烟台大学计算机学院学生
* All rights reserved.
* 文件名称：
* 作者：吴瑕
* 完成日期： 2012年 04月 10日
* 版本号：
*对任务及求解方法的描述部分
* 输入描述：实现Time 类中的运算符重载

#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);void display();//比较运算符(二目)的重载bool operator > (CTime &t);bool operator < (CTime &t);bool operator >= (CTime &t);bool operator <= (CTime &t);bool operator == (CTime &t);bool operator != (CTime &t);//二目运算符的重载CTime operator+(CTime &c);//返回c所规定的时、分、秒后的时间，例t1(8,20,25),t2(11,20,50)，t1+t2为:41:15CTime operator-(CTime &c);//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//一目运算符的重载CTime operator++(int);//后置++，下一秒CTime operator++();//前置++，下一秒CTime operator--(int);//后置--，前一秒CTime operator--();//前置--，前一秒//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};//下面实现所有的运算符重载代码。//为简化编程，请注意通过调用已有函数，利用好各函数之间的关系void CTime::setTime(int h,int m,int s){  hour=h;  minute=m;  second=s;  }void CTime:: display(){cout<<hour<<":"<<minute<<":"<<second<<endl;}//比较运算符(二目)的重载bool CTime::operator > (CTime &t){if(hour>t.hour){return true;}else {if(hour==t.hour){if(minute>t.minute){return true;}else {if(minute==t.minute){if(second>t.second){return true;}else {return false;}}else {return false;}}}else{return false;}}}bool CTime::operator < (CTime &t){if(hour<t.hour){return true;}else {if(hour==t.hour){if(minute<t.minute){return true;}else {if(minute==t.minute){if(second<t.second){return true;}else {return false;}}else {return false;}}} else{return false;}}}bool CTime::operator >= (CTime &t){if(*this<t){return false;}else{return true;}}bool CTime::operator <= (CTime &t){if(*this>t){return false;}else{return true;}}bool CTime::operator == (CTime &t){if(hour==t.hour&&minute==t.minute&&second==t.second){return true;}else{return false;}}bool CTime::operator != (CTime &t){if(*this==t){return false;}else{return true;}}//二目运算符的重载CTime  CTime::operator+(CTime &c)//返回c所规定的时、分、秒后的时间，例t1(8,20,25),t2(11,20,50)，t1+t2为:41:15{CTime  c1;c1.second=second+c.second;c1.minute=minute+c.minute;c1.hour=hour+c.hour;if(c1.second>60){c1.minute=c1.minute+c1.second/60;c1.second=c1.second%60;}if(c1.minute>60){c1.hour=c1.hour+c1.minute/60;c1.minute=c1.minute%60;}if(c1.hour>24){c1.hour=c1.hour%24;}return c1;}CTime  CTime::operator-(CTime &c)//对照+理解{CTime  c1;if(second>c.second){c1.second=second-c.second;}else{c1.second=second+60-c.second;minute=minute-1;}if(minute>=c.minute){c1.minute=minute-c.minute;}else{c1.minute=minute+60-c.minute;hour=hour-1;}c1.hour=hour-c.hour;return c1;}CTime  CTime::operator+(int s)//返回s秒后的时间{CTime  c1;c1.second=second+s;if(c1.second>=60){c1.minute=minute+c1.second/60;c1.second=c1.second%60;}else{c1.minute=minute;c1.hour=hour;}if(c1.minute>=60){c1.hour=hour+c1.minute/60;c1.minute=c1.minute%60;}else{c1.minute=minute+c1.second/60;c1.hour=hour;}if(c1.hour>24){c1.hour=hour%24;}else{c1.hour=hour;}return c1;}CTime  CTime::operator-(int s)//返回s秒前的时间{ CTime  c1;if(second>=s){c1.second=second-s;c1.minute=minute;c1.hour=hour;}else{c1.second=second+60-s;c1.minute=minute-1;if(c1.minute<0){c1.minute=59;c1.hour=hour-1;}else{c1.hour=hour;}return c1;}}//一目运算符的重载CTime CTime::operator++(int)//后置++，下一秒{CTime temp(*this);*this=*this+1;return temp;}CTime CTime::operator++()//前置++，下一秒{*this=*this+1;return (*this);}CTime CTime::operator--(int)//后置--，前一秒{CTime temp(*this);*this=*this-1;return temp;}CTime CTime::operator--()//前置--，前一秒{*this=*this-1;return (*this);}//赋值运算符的重载     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{return(*this+s);}CTime CTime::operator-=(int s)//返回s秒前的时间{return(*this-s);}void main(){CTime t1(8,20,25),t2(11,20,50),t;int s=30;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;//下面自行设计对其他运算符的重载的测试t=t1+t2;cout<<"t1+t2为：";t.display();t=t2-t1;cout<<"t2-t1为：";t.display();t=t1+s;cout<<"t1+s为：";t.display();t=t1-s;cout<<"t1-s为：";t.display();t=t1++;cout<<"t1++为：";t.display();t=++t1;cout<<"++t1为：";t.display();t=t1--;cout<<"t1--为：";t.display();t=--t1;cout<<"--t1为：";t.display();t1+=t2;cout<<"t1+=t2为：";t1.display();t1-=t2;cout<<"t1-=t2为：";t1.display();t=t1-=s;cout<<"t1-=s为：";t.display();t=t1+=s;cout<<"t1+=s为：";t.display();system("pause");}

运行结果：

上机感言：

在编写此程序时，要善于利用已实现的运算符功能，此外，要善于利用this指针。

在编写过程中要善于撞错，会有利于自己以后少出错！

为什么--t1的结果不正确呢？他的实现机制不是应该和++t1一样吗,那个运行正确，为啥这个就不对呢？愁人啊！