using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("this".CompareOrdinalIgnoreCase("This"));

    }

}

​

public static class Helper 

{

    public static bool CompareOrdinalIgnoreCase(this string string1, string string2)

    {

        var result = string.Equals(string1, string2, StringComparison.OrdinalIgnoreCase);

        return result;

    }

}