using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        string[] words = { "A", "_", "a" };

        var sortedWords = words.OrderBy(a => a, StringComparer.OrdinalIgnoreCase);

        Console.WriteLine("OrdinalIgnoreCase: " + string.Join(", ", sortedWords));

​

        sortedWords = words.OrderBy(a => a, StringComparer.CurrentCultureIgnoreCase);

        Console.WriteLine("CurrentCultureIgnoreCase: " + string.Join(", ", sortedWords));

​

        sortedWords = words.OrderBy(a => a, StringComparer.InvariantCultureIgnoreCase);

        Console.WriteLine("InvariantCultureIgnoreCase: " + string.Join(", ", sortedWords));

    }

}