Fundamentals of Computer Programming and IT by Pearson

Inheritance 469

Consider the following example:

class A1

{

protected:

int a1;

};

class A2 : public A1

{

protected:

int a2;

};

class A3: public A1

{

protected: int a3;

};

class A4: public A2,A3

{ int a4; };

In the given example, class A2 and A3 are derived from the same base class i.e., class A1 (hierarchical inheri-

tance). The classes A2 and A3 both can access variable a1 of class A1. The class A4 is derived from class A2

and class A3 by multiple inheritances. If we try to access the variable a1 of class A1, the compiler shows error

messages as given below.

(a) Error PRG58.CPP 30: Member is ambiguous: ‘A1::a1’ and ‘A1::a1’

(b) Error PRG58.CPP ...