Virtual Functions

Question 1

what is override?

Answer 1

To help address the issue of functions that are meant to be overrides but aren’t, C++11 introduced the override specifier. Override can be applied to any override function by placing the specifier in the same place const would go. If the function does not override a base class function, the compiler will flag the function as an error.

Question 2

what is final specifier when related to functions

Answer 2

It means we cannot override this function anymore

Question 3

what is final specifier when related to class inheritance

Answer 3

it means this class cannot be inherited further

Question 4

what is interface class?

Answer 4

when all the members of the class are pure virtual functions then that class is interface class.

Interface class just provides a placeholder for specifying what all functionality should be present in the base class and its upto the derived classes to implement the functionality the way they want

Question 5

what is pure virtual function?

Answer 5

virtual function whose body is set to 0 is a pure virtual function

Question 6

what is abstract class?

Answer 6

A class with one or more pure virtual function is abstact class and we cannot instantiate or have an object of abstract class.

Question 7

Do Abstract classes have a virtual table?

Answer 7

Yes abstract classes have a virtual table.
Abstract classes still have virtual tables, as these can still be used if you have a pointer or reference to the abstract class. The virtual table entry for a pure virtual function will generally either contain a null pointer, or point to a generic function that prints an error (sometimes this function is named __purecall) if no override is provided