Extension Method how to Use it

Extension Methods

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace lambda

{

    class mathclass

    {

        public int Sum(int a, int b)

        {

            return a + b;

        }

    }

}

How Extension Method is done

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using lambda;

namespace ConsoleApplication1

{

     class Program

    {

        static void Main(string[] args)

        {

            mathclass obj = new mathclass();

             Console.WriteLine( obj.substrat(12, 2));

             Console.WriteLine(obj.Divide1(12, 2));

             Console.WriteLine(obj.Sum(10, 12));

             Console.ReadLine();

        }

     }

    static class substract

     {

        public static int substrat(this mathclass obj, int num1, int num2)

         {

             return num1 - num2;

         }

        public static int Divide1(this mathclass obj, int num1, int num2)

         {

             return num1 / num2;

         }

     }

      

}