Chapter 1, Problem 14E

Program Plan Intro

Virtual function member :

• A member function that can be declared within a base class is known as virtual function.
• A derived class can redefine a virual function member.
• Preceding the function declaration, a keyword “virtual” is used for creating a virtual function in base class.
• While inheriting a class with virtual function, the virtual function is redefined by the derived class as per its needs.
• Virtual function call is been resolved at the run time whereas non virtual member functions resolves at compile time.
• Virtual function call is computationally more expensive than function call that is non virtual.
• Virtual functions use pointer invocation, indirection and a few extra instructions are required than normal member functions.
• The constructor of any class that would contain virtual functions are been required to initialize a table of pointers to its virtual member functions.

Non-virtual function member :

• Non virtual function members are resolved statistically.
• Non virtual member function is been selected statically based on the type of pointer to the object.
• Unlike virtual function member, no runtime activities happens in non virtual member functions, since the compiler resoles non virtual functions at compile time based on the type of pointer.