Validate Phone Number

   


using System;
using System.Text.RegularExpressions;

class RegexSubstitution
{
   public static void Main()
   {
      string text = "124";

      if ( !Regex.Match(text,@"^[1-9]d{2}-[1-9]d{2}-d{4}$" ).Success )
      {
         Console.WriteLine( "Invalid phone number");
      }   
   }
}