using System;

using System.Text.RegularExpressions;                   

public class Program

{

    public static void Main()

    {

        // This will return pattern  

        // will cd, cdcd, cdcdcd, ... 

        Regex regex = new Regex(@"(cd)+");  

        Match match = regex.Match("cdcdde"); 

        if (match.Success) 

        { 

            Console.WriteLine("Match Value: " + match.Value); 

        } 

        // This will either d or e  

        // which ever comes first 

         regex = new Regex(@"d|e");  

         match = regex.Match("edge"); 

        if (match.Success) 

        { 

            Console.WriteLine("Match Value: " + match.Value); 

        } 

        // Part A: the input string we are using.

        string input = "One-Two-Three";

​

        // Part B: the regular expression we use to match.

         regex = new Regex(@"One([A-Za-z0-9\-]+)Three");

​

        // Part C: match the input and write results.

         match = regex.Match(input);

        if (match.Success)

        {

            string v = match.Groups[1].Value;

            Console.WriteLine("Between One and Three: {0}", v);

        }

        // ... Input string.

        string input1 = "Left12345Right";

​

        // ... Use named group in regular expression.

        Regex expression = new Regex(@"Left(?<middle>\d+)Right");

​

        // ... See if we matched.

         match = expression.Match(input1);

        if (match.Success)

        {

            // ... Get group by name.

            string result = match.Groups["middle"].Value;

            Console.WriteLine("Middle: {0}", result);

        }

        // Done.

    }

}