Single Inheritance
Derived classes do not have access to a base class' private
data and member functions, even though they are inherited.
Even though memory is allocated for such data members,
they may only be accessed from members within the base
class itself (or friends).
This is important because giving any other class (besides a
friend) access to private information would compromise
our ability to ensure data hiding and encapsulation.
Such a compromise would decrease the value of
programming with objects.