using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Console.WriteLine(UrlIdentifierToRegexString("https://www.hotelnikkosf.com/"));

    }

    public static string UrlIdentifierToRegexString(string urlIdentifier)

        {

            if (string.IsNullOrEmpty(urlIdentifier))

            {

                return null;

            }

            else

            {

                string result = "^http(s)?://";

​

                urlIdentifier = urlIdentifier.Trim();//.ToLower();

​

                if (urlIdentifier.StartsWith("http://"))

                {

                    urlIdentifier = urlIdentifier.Replace("http://", "");

                }

                else

                {

                    urlIdentifier = urlIdentifier.Replace("https://", "");

                }

​

                if (!urlIdentifier.StartsWith("www."))

                {

                    urlIdentifier = "(www.)?" + urlIdentifier;

                }

                else

                {

                    urlIdentifier = "(www.)?" + urlIdentifier.Substring(4);

                }

​

                result = (result + urlIdentifier).Replace("/", @"\/");

​

                return result;

            }

        }

}