using System;

public class Program

{

    public static void Main()

    {

        string abcdef = MyConstants.ABC + MyConstants.DEF;

         if(string.IsInterned(abcdef) != null)

        {

            Console.Write("abcdef is interned");

        }

    }

}

​

​

public static class MyConstants {

    public const string ABC = "ABC";

    public const string DEF = "DEF";

}