Extension Methods C# Asp.net

Extension methods enable you to "add" methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type. So it’s static method and declares in static class. The declaration between a regular method and an extension method is the "this" keyword in the parameter list.  Here is the example of extension method in c# is given below

So first I have created static class and create method “CommaSplitedValues”

public static class Extension

{

    public static  String[] CommaSplitedValues(this string str)

    {

        string[] values = str.Split(',');

        for (int i = 0; i < values.Length; i++)

        {

            values[i] = values[i].Trim();

        }

        return values;

    }

   

}

How to call this method in controller

  public ActionResult CategoriesList(string CategoryName)

        {

            string EmployeeIds = "1,3,4,5,6,8";

            var items = EmployeeIds.CommaSplitedValues();

          

            return View();

        }