Sams Teach Yourself C++ in 24 Hours, fifth edition

Hour 17. Using Polymorphism and Derived Classes

What You’ll Learn in This Hour:

• What virtual methods are

• How to use virtual destructors and copy constructors

• How virtual methods enable you to use your base classes polymorphically

• The costs and dangers in using virtual methods

Polymorphism Implemented with Virtual Methods

The previous hour emphasized the fact that a Dog object is a Mammal object. This meant that the Dog object inherited the attributes (data) and capabilities (member functions) of its base class. The relationship between a base class and derived class runs deeper than that in C++.

Polymorphism allows derived objects to be treated as if they were base objects. For example, suppose you create specialized Mammal types ...