Sams Teach Yourself C++ in 21 Days

460 Day 14

The Parts of a Multiply Inherited Object ......................................................

When thePegasusobject is created in memory, both the base classes form part of the

Pegasusobject, as illustrated in Figure 14.1. This figure represents an entire Pegasus

object. This includes the new features added in the Pegasusclass and the features picked

up from the base classes.

FIGURE14.1

Multiply inherited

objects. Horse

Bird

Pegasus

Several issues arise with objects with multiple base classes. For example, what happens

if two base classes that happen to have the same name have virtual functions or data?

How are multiple base class constructors initialized? What happens if multiple base

classes both derive from the same class? The next sections answer these questions and

explore how multiple inheritance can be put to work.

Constructors in Multiply Inherited Objects....................................................

If Pegasusderives from both Horseand Bird, and each of the base classes has construc-

tors that take parameters, the Pegasusclass initializes these constructors in turn. Listing

14.4 illustrates how this is done.

LISTING14.4 Calling Multiple Constructors

0: // Listing 14.4

1: // Calling multiple constructors

2:

3: #include <iostream>

4: using namespace std;

5:

6: typedef int HANDS;

7: enum COLOR { Red, Green, Blue, Yellow, White, Black, Brown } ;

8:

9: class Horse

10: {

11: public: