Write some important rules associated with virtual functions?

Answer:

Below we are mentioning few rules for virtual function in C++.

• Virtual functions cannot be static and also cannot be a friend function of another class.
• Virtual functions should be accessed using pointer or reference of base class type to achieve run time polymorphism.
• The prototype of virtual functions should be the same in the base as well as derived class.
• They are always defined in the base class and overridden in the derived class. It is not mandatory for the derived class to override (or re-define the virtual function), in that case, the base class version of the function is used.
• A class may have a virtual destructor but it cannot have a virtual constructor.