using System;

using System.Linq;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string str1 = "221 James Street";

        string str2 = "221 James St.";

        if(str1.StartsWith(str2)){

            Console.WriteLine("1");

        }else if(str2.StartsWith(str1)){

            Console.WriteLine("2");

        }else{

            Console.WriteLine("3");

        }

        bool b = str1.Like(str2+"%");

        bool b2 = str2.Like(str1+"%");

        Console.WriteLine(b +" "+b2);

    }

}

​

​

public static class MyStringExtensions

{

  public static bool Like(this string toSearch, string toFind)

  {

    return new Regex(@"\A" + new Regex(@"\.|\$|\^|\{|\[|\(|\||\)|\*|\+|\?|\\").Replace(toFind, ch => @"\" + ch).Replace('_', '.').Replace("%", ".*") + @"\z", RegexOptions.Singleline).IsMatch(toSearch);

  }

}