inheritance&polymorphism

derived class's constructor need call the base class's constructor

Derived_class_name :: Derived_class_name(expressions)
   : Base_class_name(expressions)
{
   statements
}

Example:

Manager::Manager(string name, double salary, string dept) : Employee(name, salary) { department = dept; } int TravelClock::get_hours() const { int h = Clock::get_hours();//extend the base class member function if (is_military()) return (h + time_difference) % 24; else { h = (h + time_difference) % 12; if (h == 0) return 12; else return h; } }   To tell the C++ compiler that a particular function needs to be bound dynamically, the function must be tagged as virtual in the base class. class clock { public: Clock(bool use_military); virtual string get_location() const; virtual int get_hours() const; int get_minutes() const; bool is_military() const; private: . . . }; And in oeder to show polymorphism, we need to use base class pointer to point to both  base class and derived class.(note that base class pointer can point to derived class)