using System;

using System.Text.RegularExpressions;

​

public class Test

{

​

    public static void Main ()

    {

        var zClass = new z();

        zClass.context = null;

        IronHorse IH = zClass.context;

        if (IH == null)

        {

            Console.WriteLine("IronHorse is null");

        }

​

        // Define a regular expression for repeated words.

        Regex rx = new Regex(@"^([A-Za-z0-9 ])+$",

          RegexOptions.Compiled | RegexOptions.IgnoreCase);

​

        // Define a test string.

        string text = "Keith Moyers";

​

        // Find matches.

        MatchCollection matches = rx.Matches(text);

​

        // Report the number of matches found.

        Console.WriteLine("{0} matches found in:\n   {1}",

                          matches.Count,

                          text);

​

        // Report on each match.

        foreach (Match match in matches)

        {

            GroupCollection groups = match.Groups;

            Console.WriteLine("'{0}' repeated at positions {1} and {2}",

                              groups["word"].Value,

                              groups[0].Index,

                              groups[1].Index);

        }

    }

}

​

public class IronHorse

{

}

​

public class z

{

    public IronHorse context {get; set;}

}

​

public interface X

{

    public string context {get; set;}

}

​

// The example produces the following output to the console:

//       3 matches found in:

//          The the quick brown fox  fox jumps over the lazy dog dog.

//       'The' repeated at positions 0 and 4

//       'fox' repeated at positions 20 and 25

//       'dog' repeated at positions 50 and 54