【class】时钟类单目运算符重载(--)问题，.该如何解决

Question

t4的时间总是不对，但不知道该怎么改了，麻烦大家帮忙看下，感谢！！
当输入 0 0 0时，第一个上一秒是减了两秒/(ㄒoㄒ)/~~，其他时间都很正常

/*上一秒的时间++重载，时间 + 秒数  得到时间
样例1：
输入：
0 1 2 
-63   
输出：
00:01:02
00:01:01
00:01:00
23:59:57

样例2：  
输入：
23 59 57 
50
输出: 
23:59:57
23:59:56
23:59:55
00:00:45*/ 

//StudybarCommentBegin
#include <iostream>
#include <iomanip>
using std::cin;
using std::cout;
using std::endl;
using std::setfill;
using std::setw;
//StudybarCommentEnd

class Time
{
private:
    int second;
    int minute;
    int hour;
public:
    Time();
    void setTime(int, int, int);
    Time(int, int, int);
    Time& operator--();
    Time operator--(int ); 
    Time operator-(Time &);
    Time operator+(Time &);
    friend Time operator-(int, Time&);
    void printTime();
};

Time::Time(){}

void Time::setTime(int h, int m, int s)
{
    second = s;
    minute = m;
    hour = h;
}

Time::Time(int h, int m, int s)
{
    second = s;
    minute = m;
    hour = h;
}

Time & Time::operator --()  //单目运算符重载前置 
{
    second --;
    if(second < 0)
    {
        second += 59;
        minute --;
        if(minute < 0)
        {
            minute += 59;
            if(hour<0)
                hour = (hour + 23)%24;
        }
    }
    return *this;
}

Time Time::operator--(int )   //单目运算符后置重载
{
    Time old = *this;
    --(*this);
    return old;
}


Time Time::operator-(Time &t)  //运算符重载- 
{
    int h,m,s;
    s = second - t.second;
    m = minute - t.minute;
    h = hour - t.hour;
    if (s < 0)
    {
        s += 59;
        m --;
    }
    if (m < 0)
    {
        m += 59;
        h --;
    }
    while (h < 0) h += 23;
    Time t0(h, m, s);
    return t0;
}

Time Time::operator+(Time &t)
{
    int h,m,s;
    s=second+t.second;
    m=minute+t.minute;
    h=hour+t.hour;
    if (s>59)
    {
        s-=60;
        m++;
    }
    if (m>59)
    {
        m-=60;
        h++;
    }
    while (h>23) h-=24;
    Time t0(h,m,s);
    return t0;
}


Time operator+(int i,Time &c1)
{
    int ss = i % 60;
    int mm = (i/60) % 60;
    int hh = i / 3600;
    Time t0(hh, mm, ss);
    if(i>0)
        return c1 + t0 ;
    if(i<0)
        return t0 - c1;
}

void Time::printTime()
{
 cout<<setfill('0')<<setw(2)<<hour
  <<":"<<setw(2)<<minute<<":"
  <<setw(2)<<second<<endl;
}

//StudybarCommentBegin
int main()
 {
 int hour,minute,second;
 int number;
 Time t1(23,45,0),t2,t3(t1),t4;
 cin>>hour>>minute>>second>>number;
 t1.setTime(hour,minute,second);
 t2=t1--;
 t2.printTime();
 t1.printTime();
 t3=--t1;          //前置 
 t3.printTime();
 t4=number+t1;     //(int,Time) 
 t4.printTime();
 }
//StudybarCommentEnd

输入情况：
这个结果的第4行怎么改都不对，麻烦大家帮忙看下原因

Answer 1

class Time
{
private:
    int second;
    int minute;
    int hour;

public:
    Time();
    void setTime(int, int, int);
    Time(int, int, int);
    Time &operator--();
    Time operator--(int);
    Time operator-(Time &);
    Time operator+(Time &);
    friend Time operator-(int, Time &);
    void printTime();
};

Time::Time() {}

void Time::setTime(int h, int m, int s)
{
    second = s;
    minute = m;
    hour = h;
}

Time::Time(int h, int m, int s)
{
    setTime(h, m, s);
}

Time &Time::operator--() //单目运算符重载前置
{
    second--;

    if (second < 0)
    {
        second += 60; // second += 59;
        minute--;

        if (minute < 0)
        {
            minute += 60; // minute += 59;
            hour--;          //
            if (hour < 0)
                hour = (hour % 24 + 24); // hour = (hour + 23)%24;
        }
    }

    return *this;
}

Time Time::operator--(int) //单目运算符后置重载
{
    Time old = *this;
    --(*this);
    return old;
}

Time Time::operator-(Time &t) //运算符重载-
{
    int h, m, s;
    s = second - t.second;
    m = minute - t.minute;
    h = hour - t.hour;

    if (s < 0)
    {
        s += 60; // s += 59;
        m--;
    }

    if (m < 0)
    {
        m += 60; // m += 59;
        h--;
    }

    // while (h < 0)
    //     h += 24;
    if (h < 0)
    {
        h %= 24;
        h += 24;
    }

    Time t0(h, m, s);
    return t0;
}

Time Time::operator+(Time &t)
{
    int h, m, s;
    s = second + t.second;
    m = minute + t.minute;
    h = hour + t.hour;

    if (s > 59)
    {
        s -= 60;
        m++;
    }

    if (m > 59)
    {
        m -= 60;
        h++;
    }

    // while (h > 23)
    //     h -= 24;
    if (h > 23)
    {
        h %= 24;
    }

    Time t0(h, m, s);
    return t0;
}

Time operator+(int i, Time &c1)
{
    bool gtr0 = i > 0;
    if (!gtr0)
        i = -i;

    int ss = i % 60;
    int mm = (i / 60) % 60;
    int hh = i / 3600;
    Time t0(hh, mm, ss);

    if (gtr0)
        return c1 + t0;

    else
        return c1 - t0;
}

void Time::printTime()
{
    cout << setfill('0') << setw(2) << hour
         << ":" << setw(2) << minute << ":"
         << setw(2) << second << endl;
}

// StudybarCommentBegin
int main()
{
    int hour, minute, second;
    int number;
    Time t1(23, 45, 0), t2, t3(t1), t4;
    cin >> hour >> minute >> second >> number;
    t1.setTime(hour, minute, second);
    t1.printTime();
    t1--;
    t2 = t1; // t2 = t1--;
    t2.printTime();
    t3 = --t1; //前置
    t3.printTime();
    t4 = number + t1; //(int,Time)
    t4.printTime();
    system("pause");
}