C++中++运算符的重载

     void showTime() const;
     Clock& operator ++();
     Clock operator ++(int);
 private:
     int hour,minute,second;
 };
 Clock::Clock(int hour,int minute,int second){
     if(<=hour&&hour<&&<=minute&&minute<&&<=second&&second<)
        {
            this->hour=hour;
            this->minute=minute;
            this->second=second;
        }
     else
         cout<<"Time error!"<<endl;
 }

 void Clock::showTime() const
 {
     cout<<hour<<":"<<minute<<":"<<second<<endl;
 }

 Clock& Clock::operator ++()
 {
     second++;
     if(second>=)
     {
         second-=;
         minute++;
         if(minute>=)
         {
             minute-=;
             hour=(hour+)%;
         }
     return *this;
     }
 }

 Clock Clock::operator ++(int)
 {
     Clock old=*this;
     ++(*this);
     return old;
 }

 int main()
 {
     Clock myClock(,,);
     cout<<"First time output:";
     myClock.showTime();
     cout<<"Show myClock++:   ";
     (myClock++).showTime();
     cout<<"Show ++myClock:   ";
     (++myClock);
     myClock.showTime();
     return ;
 }