贺老师的教学链接  本课讲解

默认构造函数(default constructor)

class Time
{
public:
     Time( );
     void show_time();  
  private:
     int hour;  
     int minute;
     int sec;
};
Time::Time( )
{
     hour=0;                 
     minute=0;
     sec=0;
}