Polymorphism potx

Polymorphism

Chapter 7

Polymorphism is the ability that helps in executing

different operations in response to the same

message. In OOP, you can implement

polymorphism by creating more than one function

within a class that have the same name. The

difference in the functions lies in the number and the

types of parameters passed to each function.

This chapter introduces the concept of

polymorphism. It explains how to implement

function overloading and operator overloading.

In this chapter, you will learn to:

 Describe polymorphism

 Implement function overloading

 Implement operator overloading

Objectives

¤NIIT Polymorphism 7.3

The term polymorphism was derived from the Greek words ‘poly’ and ‘morphos’, which

mean ‘many’ and ‘forms’, respectively. In OOP, polymorphism is often expressed by the

phrase “one interface, multiple functions”. This expression means that polymorphism

allows one interface to be used for multiple functions. You can apply polymorphism for

reducing the complexity within the functions of a class of your program.

Polymorphism can either be static or dynamic. In static polymorphism the response to a

function is decided at compile time. In dynamic polymorphism the response to the

function is decided at run time.

Static polymorphism refers to an entity, which exists in various forms simultaneously.

The concept of static polymorphism is analogous to the role of a woman who can be a

wife, a mother, a daughter, a sister, and an executive at the same time.

The mechanism of linking a function with an object during compile time is called early

binding. It is also known as static binding.

C# uses two approaches to implement static polymorphism. These are:

„ Function Overloading

„ Operator Overloading

Function Overloading

This approach allows using the same name for two or more functions. Each redefinition of

a function must use different types of parameters, sequence of parameters, or a number of

parameters. The type, sequence, or number of parameters for a function is called the

function signature. When you have multiple functions with the same name, the compiler

identifies the function based on the parameters to the function.

Consider an example, to understand the benefit of function overloading where you need a

function that converts distance in kilometers to miles, and kilometers can either be an

integer or a float. One approach can be to have two functions of different names, as

shown in the following code:

int ConvertInteger(int km);

int ConvertFloat(float km);

Introducing Polymorphism

Static Polymorphism