// C# Extension Method

// Doc: https://csharp-extension.com/en/method/1002356/enum-notin

​

// @nuget: Z.ExtensionMethods

​

using System;

using System.ComponentModel;

public class Program

{

    private static void Display(Color color)

    {

        // C# Extension Method: Enum - NotIn

        if (color.NotIn(Color.DarkSeaGreen, Color.RosyBrown, Color.RosyBrown))

        {

            Console.WriteLine("{0} doesn't exists in the list.", color);

        }

        else

        {

            Console.WriteLine("{0} exists in the list.", color);

        }

    }

​

    public static void Main()

    {

        Display(Color.BlanchedAlmond);

        Display(Color.RosyBrown);

    }

​

}

​

public enum Color

{

    [Description("Blanched Almond Color")]

    BlanchedAlmond = 1,

    [Description("Dark Sea Green Color")]

    DarkSeaGreen = 2,

    [Description("Deep Sky Blue Color")]

    DeepSkyBlue = 3,

    [Description("Rosy Brown Color")]

    RosyBrown = 4

}

​