using System;

using System.Text.RegularExpressions;

​

public class Foo

{

    public static void Main()

    {

        var x = "foobar";

        var r = new Regex("(?<tags>foo|bar)+");

        var matches = r.Matches(x);

        foreach (Match match in matches)

        {

            Console.WriteLine(match.Groups["tags"].Value);

        }

    }

}