Virtual Functions

Virtual Functions

1. A member function that is dynamically bound to function calls

   • the function will dynamically assign the methd
     • Must have a virtual destructor but only needs to be in the base class
   • Can be invoked via a dereferenced pointer or reference object

2. Polymorphism

   • function that can take arguments of different types

3. Determination of which virtual function to use cannot always be made at run time

   • Implementation of virtual function is by virtual table
     • All the objects in a class contain one data member called virtual table pointer which points to an array of function pointers
       • When virtual pointer is envoked, actual function is determined by following the pointer and looking up the address in a table