What do you mean by Polymorphism?

 Polymorphism, as the name suggest represents many forms.["Poly" means many, and "morph" means form].Polymorphism allows methods to behave differenlty in different situations depending on the input/scenario.The polymorphic method methods behaves in the same consistent manner with all the communicating objects even though their implementations varies.

In polymorphism the behaviour of method is decided during run time depending on the type of input passed to the method. The process used by object-oriented programming languages to implement polymorphism is called dynamic binding.




Polymorphism Example

 Polymorphism can be implemented with inheritence. Base class must have virtual methods defined and implemented. Child Class can override these virtual methods by providing their own implementation as per requirement.During run time the complier decides the implemetation to be executed depending upon the type of the object requesting the execution. Thus calling the method of the base class causes the execution of the required child class.

Visit http://www.codeproject.com/Articles/1445/Introduction-to-inheritance-polymorphism-in-C

for more details on implementation and real time examples on Polymorphism.

Note : In C#, every type is polymorphic. This is because all types, including user-defined types is inherited from Object.

Why do we need object oriented programming?

The Object Oriented Programming Languages directly represent the real life objects like Automobile, Flower, Pen etc. The most used  and powerful features of OO programming are polymorphism, inheritance and encapsulation.

[Tip to remember : PIE - Polymorphism, Inheritence and Encapsulation.].

Benefits of OOP

Reusable: Using the concept of inheritance the implementation of other class can be used. For example, if we have a to create classes for birds, we can have a prent class Bird which can implement functionality fly(). This functionality remains same for all child bird classes which inherit the parent class Bird.

Simple: OOP represents the real life objects. This real mapping easy understanding, reduction of complexity and makes the program structure simpler.

Modular: Usage of objects, classes etc helps in clubbing the relevent functinality together. This helps in easy understanding if the system and also makes the implementation independent of each other. This makesThis in turn will make it very easy to modify the system when required.  

Maintainable: It becomes very easy to make minor changes to the system as this approach is modular and is loosely coupled. The entire system need not be modified to incorporate the changes and hence reduces the development time.

Extensible: It is specified that the system becomes loosely coupled. This makes it easy to plug in more features to the system. This way we can extend the application to provide more features to the user. 

Summary

Considering the above points we can conclude that using OOP can definetly help us in providing quality code. This can be achieved as we will be able to reuse the code which helps us avoid code and test the reuse sections. This not only helps us in reducing the defects but can also reduces the development time.

Maintainence of the application becomes very easy as OOP is more extensible, reusable and modular.