Do derived classes need their own version of a virtual function declared on base?

Question

For instance, the class Plant has a virtual void info() method. The class flower derives from Plant .
Is Plant obligated to have its own implementation of the method?

Answer 1

No.

Base classes do not need their own implementation of a virtual method that is implemented by a dervided class. However, they can have an implementation.

To skip the implementation in the base class, just make it pure virtual, eg

virtual void info() = 0;

In that case any derived classes - or to be more specific: any derived class that you want to have an instance of - needs to implement the virtual method.

Answer 2

If the function is pure virtual , that is declared virtual void info() = 0; , then No. Otherwise Yes.