Вопрос по ООП

class time
{
    private:
    int hours;
    int minutes;
    public:
    int sum_time(time object,  days day);
};
 
class days
{
    private:
    int day_num;
};
 
int time::sum_time(time object,  days day)
{
   int total_hours;
   total_hours = this.hours + object.hours;
   object.hours = total_hours;
   day.day_num = 0;
   return total_hours;
}

class CDays
{
    int day_num;
 
public:
    int GetDay() const {return day_num;}
    void SetDay(int number){ day_num = number;}
};
 
class CTime
{
private:
    CDays day;
    int hours;
    int minutes;
 
public:
 
    int sum(CTime object, CDays day);
};
 
int CTime::sum(CTime object, CDays day)
{
    int total_hours = 0;
    total_hours = object.hours + 24*day.GetDay();
    object.hours = total_hours;
    day.SetDay(0);
    return total_hours;
}

class TIME
{
    private: 
    int hours;
    public:
    int sum_time(TIME object)
    {
         int result_time;
         result_time = object.hours + this.hours;
         object.hours = 10; // ВОТ ЗДЕСЬ ОЧЕНЬ ИНТЕРЕСУЕТ
         return result_time;
    }
};