samiksc

 Profile Answers by samiksc 

• Jan 20th, 2006

 

To achieve runtime polymorphism.

For a virtual function which is defined in both the base and derived classes, the decision of which implementation to call is taken at runtime depending on the type of object, and NOT depending on the declaration type of pointer/reference.

Virtual functions slow down execution due to runtime binding -- so only those methods which will be redefined by the derived classes should be declared as virtual.