using System;
using System.Text.RegularExpressions;
 
public class Example
{
   public static void Main()
   {
      string[] myStrings = { "1-2&3-4",
                             "ABC#123", 
                             "12+abc-34#" };
      string pattern = @"^[a-z0-9&#+.-]+$";
      foreach (string myString in myStrings)
         Console.WriteLine("{0} {1} a valid string.", 
                           myString, 
                           Regex.IsMatch(myString, pattern) ? "is" : "is not");
   }
}

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