Polymorphism

What is Polymorphism?

Polymorphism means one name many forms.

One function behaves different forms.

In other words, "Many forms of a single object is called Polymorphism."

Real World Example of Polymorphism:

Example-1: 

A Teacher behaves to student.

A Teacher behaves to his/her seniors.

Here teacher is an object but attitude is different in different situation.

Example-2: 

Person behaves SON in house at the same time that person behaves EMPLOYEE in office.

Example-3: 

Your mobile phone, one name but many forms

• As phone
• As camera
• As mp3 player
• As radio

To Read Polmorphism in Detail click following link:-

Polymorphism in .Net

Difference between Abstraction andEncapsulation :-

Abstraction	Encapsulation
1. Abstraction solves the problem in the design level.	1. Encapsulation solves the problem in the implementation level.
2. Abstraction is used for hiding the unwanted data and giving relevant data.	2. Encapsulation means hiding the code and data into a single unit to protect the data from outside world.
3. Abstraction lets you focus on what the object does instead of how it does it	3. Encapsulation means hiding the internal details or mechanics of how an object does something.
4. Abstraction- Outer layout, used in terms of design. For Example:-  Outer Look of a Mobile Phone, like it has a display screen and keypad buttons to dial a number.	4. Encapsulation- Inner layout, used in terms of implementation. For Example:- Inner Implementation detail of a Mobile Phone, how keypad button and Display Screen are connect with each other using circuits.

The easier way to understand Abstraction and encapsulation is as follows:-

Real World Example:- 

Take an example of Mobile Phone:- 

You have a Mobile Phone, you can dial a number using keypad buttons. Even you don't know how these are working internally. This is called Abstraction. You have the only information that is needed to dial a number. But not its internal working of mobile.

But how the Mobile Phone internally working?, how keypad buttons are connected with internal circuit? is called Encapsulation.

Summary:

"Encapsulation is accomplished by using Class. - Keeping data and methods that accesses that data into a single unit" 

"Abstraction is accomplished by using Interface. - Just giving the abstract information about what it can do without specifying the back ground details" 

"Information/Data hiding is accomplished by using Modifiers - By keeping the instance variables private or protected."

Encapsulation

Encapsulation: 

Wrapping up data member and method together into a single unit (i.e. Class) is called Encapsulation.

Encapsulation is like enclosing in a capsule. That is enclosing the related operations and data related to an object into that object.

Encapsulation is like your bag in which you can keep your pen, book etc. It means this is the property of encapsulating members and functions.

    class Bag

    {

        book;

        pen;

        ReadBook();

    }

Encapsulation means hiding the internal details of an object, i.e. how an object does something.

Encapsulation prevents clients from seeing its inside view, where the behaviour of the abstraction is implemented.

Encapsulation is a technique used to protect the information in an object from the other object.

Hide the data for security such as making the variables as private, and expose the property to access the private data which would be public.

So, when you access the property you can validate the data and set it.

Example:

class Demo

{

   private int _mark;

   public int Mark

   {

     get { return _mark; }

     set { if (_mark > 0) _mark = value; else _mark = 0; }

   }

 }

Real world Example of Encapsulation:-

Let's take example of Mobile Phone and Mobile Phone Manufacturer

Suppose you are a Mobile Phone Manufacturer and you designed and developed a Mobile Phone design(class), now by using machinery you are manufacturing a Mobile Phone(object) for selling, when you sell your Mobile Phone the user only learn how to use the Mobile Phone but not that how this Mobile Phone works.

This means that you are creating the class with function and by making object (capsule) of it you are making availability of the functionality of you class by that object and without the interference in the original class.

Example-2: 

TV operation 

It is encapsulated with cover and we can operate with remote and no need to open TV and change the channel.

Here everything is in private except remote so that anyone can access not to operate and change the things in TV.

Inheritance: 

When a class acquire the property of another class is known as inheritance.

Inheritance is process of object reusability.

For example, A Child acquire property of Parents.

public class  BaseClass

    {

        public  BaseClass()

        {

            Console.WriteLine("Base Constructor.");

        }

        public void print()

        {

            Console.WriteLine("I'm a Base Class.");

        }

    }

    public class ChildClass :  BaseClass

    {

        public ChildClass()

        {

            Console.WriteLine("Child Constructor.");

        }

        public static void Main()

        {

            ChildClass child = new ChildClass();

            child.print();

        }

    }

Output:

    Base  Constructor.
    Child Constructor.
    I'm a Parent Class.