第九周实验报告（二）

接第八周任务2，定义CTime类中的<<与>>运算符重载，实现时间的输入输出。

 

#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);      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:41:15      CTime operator-(CTime &c);//对照+理解      CTime operator+(int s);//返回s秒后的时间      CTime operator-(int w);//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 w);//返回s秒前的时间       friend istream & operator >>(istream & ,CTime &);    friend ostream & operator <<(ostream &,CTime &);};  //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    int main()  {      CTime t1,t2,t;      cout<<"请输入t1"<<endl;    cin >> t1;    cout<<"请输入t2"<<endl;    cin >> t2;     cout<<"t1为：";      cout<<t1;      cout<<"t2为：";      cout<<t2;      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<<"t1与t2的和为";      t = t1 + t2;      cout<<t;           cout<<"差"<<endl;      t = t1 - t2;      cout<<t;            cout<<"在t1的基础上加2s";       t = t1 + 2;     cout<<t;            cout<<"在t1的基础上减2s";       t = t1 - 2;      cout<<t;            cout<<"t1前置加1s";      ++t1;      cout<<t;           cout<<"t1后置加1s";      t1++;      cout<<t;           cout<<"t1前置减1s";      --t1;      cout<<t;            cout<<"t1后置减1s";      t1--;      cout<<t;            cout<<"t1+=t2    ";      t1+=t2;      cout<<t;            cout<<"t1-=t2    ";      t1-=t2;      cout<<t;           cout<<"t1+=2     ";      t1+=2;      cout<<t;           cout<<"t1-=2     ";      t1-=2;      cout<<t;                        cout<<endl;      system("pause");      return 0;      //下面自行设计对其他运算符的重载的测试        }  /*void CTime::setTime(int h,int m,int s)  {      hour = h;      minute = m;      second = s;  }  void CTime::display()  {      cout<<hour<<":"<<minute<<":"<<second<<endl;  } */bool CTime::operator>(CTime &t)  {      if(hour>t.hour)      {              return true;      }      else          return false;  }  bool CTime::operator<(CTime &t)  {      if(hour<t.hour)      {              return true;      }      else          return false;  }  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(hour==t.hour&&minute==t.minute&&second==t.second)          return true;      else          return false;  }  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(hour!=t.hour||minute!=t.minute||second!=t.second)          return true;      else          return false;  }  CTime CTime::operator+(CTime &c)  {      CTime a;      a.hour = hour + c.hour;            if(a.hour>24)          a.hour -= 24;            a.minute = minute + c.minute;            if(a.minute>=60)      {          a.minute -= 60;          a.hour+=1;      }      a.second = second + c.second;      if(a.second>=60)      {          a.second -= 60;          a.minute+=1;          if(a.minute>=60)          {              a.minute -= 60;              a.hour+=1;          }      }      return a;  }  CTime CTime::operator -(CTime &c)  {        int h,m,s;                h = hour - c.hour;        m = minute - c.minute;        s = second - c.second;        if(s<0)        {               s=(-s);               m--;        }         if(m<0)        {               m=60+m;               h--;        }        while (h<0) h=-h;        CTime a(h,m,s);                       return a;                 }  CTime CTime::operator+(int s)  {        CTime a;      a.second = second + s;      if(a.second>=60)      {          a.second -= 60;          a.minute=minute+1;      }      else      a.minute = minute;      if(a.minute>=60)          {              a.minute -= 60;              a.hour=hour+1;          }          else          a.hour = hour;      return a;  }  CTime CTime::operator-(int w)  {        int h,m,s;        h = hour ;        m = minute ;        s = second - w;        if(s<0)        {               s=(-s);               m--;        }        if(m<0)        {               m=60+m;               h--;        }        if(h<0)        {               h=(-h);        }        CTime a(h,m,s);        return a;  }  CTime CTime::operator++(int)//后置++，下一秒   从这里开始以后使用重载过的运算符，使程序更为简单  {        CTime t=*this;          //*this指的是指向CTime类的成员对象，因为定义的重载的运算符需要一个是类才自动使用      *this=*this+1;          //这里定义了t=*this是因为需要后置一下秒，所以返回的是原来的类的对象成员，并且在原来的基础上*this+1s      return t;    }        CTime CTime::operator++()//前置++，下一秒    {        *this=*this+1;         //这里没有定义CTime t是因为前置返回的是变化后的类的对象成员      return *this;    }        CTime CTime::operator--(int)//后置--，前一秒   //与++雷同  {        CTime t=*this;        *this=*this-1;        return t;    }        CTime CTime::operator--()//前置--，前一秒    {        *this=*this-1;        return *this;    }    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;    }  ostream & operator <<(ostream & output,CTime &t){        output << t.hour << ":"<<t.minute<<":"<<t.second<<endl;;        return output;}istream & operator >>(istream & input,CTime &t){        input >> t.hour>>t.minute>>t.second;        return input;}                 

 

 

总结：重载流插入运算符和流提取运算符

             形式   istream & operator >> (istream &,类&)；

                        ostream & operator<<(ostream&，类&)；

          并且重载的在类中的必须是友元函数。