Ivor Horton's Beginning Visual C++ 2012

INHERITANCE IN CLASSES

When you define one class based on an existing class, the new class is referred to as a derived class. A derived class automatically contains all the data members of the class that you used to define it and, with some restrictions, the function members as well. The class is said to inherit the data members and function members of the class on which it is based.

The only members of a base class that are not inherited by a derived class are the destructor, the constructors, and any member functions overloading the assignment operator. All other function members, together with all the data members of a base class, are inherited by a derived class. Of course, the reason for certain base members not being inherited is that a derived class always has its own constructors and destructor. If the base class has an assignment operator, the derived class provides its own version. When I say these functions are not inherited, I mean that they don’t exist as members of a derived class object. However, they still exist for the base class part of an object, as you will see.

What Is a Base Class?

A base class is any class that you use as a basis for defining another class. For example, if you define a class, B, directly in terms of a class, A, A is said to be a direct base class of B. In Figure 9-1, the CCrate class is a direct base class of CBeerCrate. When a class such as CBeerCrate is defined in terms of another class, CCrate, CBeerCrate is said to be derived from CCrate ...