Using Extension Methods in C#

Following is an example use of an Extension method in C#.

Imagine you have a class written by someone else and you are not allowed to do any modification to the class.

   public class Class1

    {

        public int MyProperty { get; set; }

    }

You have come up with the following calculation and want to have it in the Class1, so that others could use it without rewriting the calculation.

int sum = p.MyProperty * 5;

Now, incomes the extension method.

public static class myextention

    {

        public static int test(this Class1 p)

        {

           

            return p.MyProperty * 5;

        }

    }

After creating the extension method, you can now call the test function as it’s defined in the Class1 itself.

Class1 c = new Class1();

int extensionSum = c.test();