Inheritance

Question 1

What is subtyping?

Answer 1

When we establish an ‘is-a’ relationship between one type and another type.

Question 2

What are parent classes know is in C++?

Answer 2

base or virtual classes and derived classes.

Question 3

How do you type extend Animal class?

Answer 3

: public Animal

Question 4

What happens if the specifier for the class extension is public?

Answer 4

base class public and protected members keep the same access.

Question 5

What happens if the specifier for the class extension is protected?

Answer 5

base class public and protected members are protected.

Question 6

What happens if the specifier for the class extension is private?

Answer 6

Base class public and protected members are private.

Question 7

What is a protected member variable?

Answer 7

Restricts access to certain class members to the class itself and its derived classes. Allowing access to derived classes but not external.

Question 8

What is polymorphism?

Answer 8

Same function names with different functionality due to parameters and typing.

Question 9

How is polymorphism achieved in C++?

Answer 9

Virtual functions/classes

Question 10

What are virtual functions/classes?

Answer 10

Mechanisms to declare a function in a base class and for that function with the same name and type to be implemented in a derived class.

Question 11

What can derived classes do to public/protected code in the base class?

Answer 11

Override it.

Question 12

How do we determine which specific function for virtual functions to use?

Answer 12

Based on the type of object used at runtime (runtime polymorphism)

Question 13

What is multiple inheritance?

Answer 13

When a derived class inherits from two+ base classes.

Question 14

What are common ancestors?

Answer 14

Classes that inherit the same class through multiple inheritance.

Question 15

What is the diamond problem?

Answer 15

The ambiguity that arises when a class inherits from classes that have a common ancestor, leading to potential conflicts.

Question 16

How do we solve the diamond problem?

Answer 16

Virtual keyword for classes

Question 17

What are virtual classes?

Answer 17

Using the virtual keyword, prevents multiple copies of the base class, resolving the ambiguity caused by ancestors and multiple inheritance. Allows a derived class to inherit from a common base class only once.

Question 18

What is a pure virtual function and what does it to do a base class??

Answer 18

A pure virtual function is a function that requires an implementation by the derived class, meaning the base class is abstract and cannot be instantiated.

Question 19

What is an abstract class?

Answer 19

A class that contains at least one pure virtual function and cannot be instantiated directly, serving as a blueprint for derived classes to implement specific functionality.

Question 20

What is the syntax for a pure virtual function?

Answer 20

Use the virtual key word and have the function = 0 in the function prototype, e.g.:

virtual void doSomething() = 0;