Interface V/s Without Interface?

Question

I have read a lot of logics and examples related to interface. but i never get any satisfied real use of interface. I always work in raw programming.  

 

* One more point people says further implementation is easy using interface ? How is it possible? Suppose an interface is inherit by 100 classes. 

 

Suppose in an example below :

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace InterFaceDemo

{

interface IOne

{

void ONE();//Pure Abstract Method Signature

}

interface ITwo

{

void TWO();

}

interface IThree:IOne

{

void THREE();

}

interface IFour

{

void FOUR();

}

interface IFive:IThree

{

void FIVE();

}

interface IEVEN:ITwo,IFour

{

}

class ODDEVEN:IEVEN,IFive//Must Implement all the abstract method, in Derived class.

{

public void ONE()//Implementation of Abstract Method.

{

Console.WriteLine("This is ONE");

}

public void TWO()

{

Console.WriteLine("This is TWO");

}

public void THREE()

{

Console.WriteLine("This is THERE");

}

public void FOUR()

{

Console.WriteLine("This is FOUR");

}

public void FIVE()

{

Console.WriteLine("This is FIVE");

}

}

}

Program.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace InterFaceDemo

{

class Program

{

static void Main(string[] args)

{

Console.WriteLine("This is ODD");

IFive obj1 = new ODDEVEN();

obj1.ONE();

obj1.THREE();

obj1.FIVE();

Console.WriteLine("\n\nThis is EVEN");

IEVEN obj2 = new ODDEVEN();

obj2.TWO();

obj2.FOUR();

Console.ReadLine();

}

}

}

The following is the output:

 Everyone can do same task without interface then what is exact use.

 

 

using System;

namespace vaibhav

{

    class ODDEVEN

    {

        public void ONE()

        {

            Console.WriteLine("This is ONE");

        }

        public void TWO()

        {

            Console.WriteLine("This is TWO");

        }

        public void THREE()

        {

            Console.WriteLine("This is THERE");

        }

        public void FOUR()

        {

            Console.WriteLine("This is FOUR");

        }

        public void FIVE()

        {

            Console.WriteLine("This is FIVE");

        }

    }

    public class SametaskWithoutinterface

    {

        public static void Main()

        {

            Console.WriteLine("This is ODD");

            ODDEVEN obj1 = new ODDEVEN();

            obj1.ONE();

            obj1.THREE();

            obj1.FIVE();

            Console.WriteLine("\n\nThis is EVEN");

            ODDEVEN obj2 = new ODDEVEN();

            obj2.TWO();

            obj2.FOUR();

            Console.ReadLine();

        }

    }

}

 

 

 

 

Both example will gives you same result then why did i choose interface?