2023.4.23

#include <iostream>
using namespace std;
class Clock
{
public:
    Clock(int hour = 0,int minute = 0,int second = 0);
    void showTime()const;
    Clock& operator++();
    Clock operator++(int);
private:
    int hour,minute,second;
};
Clock::Clock(int hour,int minute ,int second )
{
    if(0<=hour&&hour<24&&0<=minute&&minute<60&&0<=second&&second<60)
    {
        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>=60)
    {
            second-=60;
            minute++;
            if(minute>=60)
        {
            minute-=60;
            hour = (hour+1)%24;
        }
    }
    return *this;
}
Clock Clock::operator++(int)
{
   Clock old = *this;
   ++(*this);
   return old;
}
int main()
{
    Clock myclock(23,59,59);
    cout<<"First time output:";
    myclock.showTime();
    cout<<"show ++myclock:";
    (++myclock).showTime();
    cout<<"show myclock++:";
    (myclock++).showTime();
    return 0;
}