Friend Classes
	• When a class (declaring class) declares another class (friend class) to be a friend, the friend class' member functions can invoke the protected or private member functions or use the protected or private data members of the declaring class. • To do so, the friend class must have access to an object of the declaring class' type. • This can be done by having an object of the friend class as a data member or a pointer to an object of the friend class.