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Unit 9: Inheritance
9.3.2 Ambiguity in Multipath Inheritance Notes
Sometimes we need to apply two or more types of inheritance to design a program and this type
of inheritance are called hybrid inheritance. But in hybrid inheritance, if multiple paths exit
between a base class and derived class through different intermediate classes, then derived class
inherits the members of the base class more than one time and it results in ambiguity. Here, base
class is called indirect base class and intermediate base classes are called direct base classes.
To avoid this ambiguity, the indirect base class is made virtual base class and to define base class
as virtual, a keyword virtual is appended when extending the direct base classes from the
indirect base class as given in the example. In this way, when we define the indirect base class
virtual, compiler take care that only one copy of that class is inherited, regardless of how many
inherited paths exist between the virtual base class and the derived class.
Figure 9.1: Hybrid Inheritance
Example:
class student
{
protected:
char course[20];
char name[20];
int enroll;
};
class exam:virtual public student
{
protected:
char etype[20];
int msub1;
int msub2;
int msub3;
};
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