Chapter 11 By Robert Lafore

1. Virtual Functions:
Chapter 11:
Ms. Munazza Mah Jabeen
Assistant Professor of Computer Science

2. Virtual Functions:
• Virtual means existing in appearance but not in reality. a program that
appears to be calling a function of one class may in reality be calling a
function of a different class.
• Completely different functions are executed by the same function call
i.e. draw(). This is called polymorphism, which means different forms.
• For the polymorphic approach to work, several conditions must be met.
• First, all the different classes of shapes, such as balls and triangles, must be
descended from a single base class.
• Second, the draw() function must be declared to be virtual in the base class.

3. Normal Member Functions Accessed with Pointers:

4. Virtual Member Functions Accessed with Pointers:

5. Binding:
Polymorphism is classified into 2 branches:
• Compile Time Polymorphism/Early Binding/Static
Binding
• Runtime Polymorphism/Late Binding/Dynamic
Binding
What is Binding?
• For every function call; compiler binds or links the
call to one function definition.
• This linking can happen at 2 different time
• At the time of compiling program, or
• At Runtime

6. Friend Functions & friend Classes:

7. Assignment and Copy Initialization/this pointer: