C++ How to Program, 10/e

12.1 Introduction

We now continue our study of OOP by explaining and demonstrating polymorphism with inheritance hierarchies. Polymorphism enables you to “program in the general” rather than “program in the specific.” In particular, you can write programs that process objects of classes that are part of the same class hierarchy as if they were all objects of the hierarchy’s base class. As we’ll soon see, polymorphism works off base-class pointer handles and base-class reference handles, but not off name handles.

Implementing for Extensibility

With polymorphism, you can design and implement systems that are easily extensible— new classes can be added with little or no modification to the general portions of the program, as long as the new ...