Page 217 - DCAP404 _Object Oriented Programming

Object-oriented Programming Ajay Kumar Bansal, Lovely Professional University

Notes Unit 10: Virtual Functions and Polymorphism

CONTENTS
Objectives
Introduction
10.1 Virtual Functions

10.1.1 Late Binding
10.2 Pure Virtual Functions
10.3 Abstract Classes

10.4 Polymorphism
10.5 Summary
10.6 Keywords
10.7 Review Questions
10.8 Further Readings

Objectives

After studying this unit, you will be able to:
 Demonstrate the virtual functions
 Recognize the pure virtual functions

 Describe the abstract classes
 Explain the polymorphism

Introduction

By default, C++ matches a function call with the correct function definition at compile time. This
is called static binding. You can specify that the compiler match a function call with the correct
function definition at run time; this is called dynamic binding. You declare a function with the
keyword virtual if you want the compiler to use dynamic binding for that specific function.

10.1 Virtual Functions

Virtual functions, one of advanced features of OOP is one that does not really exist but it appears
real in some parts of a program. This section deals with the polymorphic features which are
incorporated using the virtual functions.
The general syntax of the virtual function declaration is:
class use_defined_name{

private:
public:
virtual return_type function_name1 (arguments);
virtual return_type function_name2(arguments);

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