Validate address
using System; using System.Text.RegularExpressions; class RegexSubstitution { public static void Main() { string text = "124 street"; if ( !Regex.Match( text, @"^[0-9]+\s+([a-zA-Z]+|[a-zA-Z]+\s[a-zA-Z]+)$" ).Success ) { Console.WriteLine( "Invalid address"); } } }