Unit_12: Multi Inheritance

Question 1

What is the main issue with multiple inheritance in C++?

Answer 1

Ambiguity — the child class may inherit methods with the same name from multiple parents, and it must disambiguate which method to use.

Question 2

How can a programmer resolve ambiguity caused by multiple inheritance?

Answer 2

By using fully qualified names, like A::foo(), to specify exactly which parent class’s method should be called.

Question 3

Why is multiple inheritance considered awkward in practice?

Answer 3

Because the programmer must remember and track which method comes from which parent, potentially many levels up the hierarchy. It increases complexity and the chance of errors.

Question 4

What is the diamond problem in object-oriented programming?

Answer 4

diamond problem occurs in multiple inheritance when a class inherits from two classes that both inherit from a common base class, causing ambiguity due to duplicated members from the base class.

Question 5

Why does class C in the diagram have two copies of class A’s data?

Answer 5

Because both classes B and C inherit from A separately, and class D inherits from both B and C, causing it to receive two separate copies of A’s members—one from each path.

Question 6

How does the diamond problem lead to ambiguity in a program?

Answer 6

It creates confusion about which inherited member (from class A) should be used when the subclass (like D) tries to access it, leading to potential errors or unexpected behavior.

Question 7

What is virtual inheritance used for in C++?

Answer 7

Virtual inheritance is used to prevent multiple “instances” of a base class when using multiple inheritance, helping to resolve the diamond problem.

Question 8

In the diagram, how many name variables does TA have and why?
NamedPerson. -> ( string name)
|
| virtual inheritance
v
NumberedPerson -> (int number)
/ \
/ \
/ “Regular” \
/ inheritance \
v v
Employee Student
\ /
\ /
v v
TA

Answer 8

TA has only one name because NamedPerson is inherited virtually, preventing duplication.

Question 9

Why does the TA object end up with two different number values?

Answer 9

Because both Employee and Student inherit NumberedPerson using regular (non-virtual) inheritance, so TA ends up with two separate copies of number.