Gr(a|e)y
using System; using System.Text.RegularExpressions; public class MainClass { public static void Main() { Regex n = new Regex("Gr(a|e)y"); MatchCollection mp = n.Matches("Green, Grey, Granite, Gray"); for (int i = 0; i < mp.Count; i++) { Console.WriteLine("Found '{0}' at position {1}",mp[i].Value, mp[i].Index); } } }