02.8a.07.2.WebExtraction

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class DomainNameExtract
{
    /*
    ** Method 1 (using the build-in Uri-object)
    */
    public static string ExtractDomainNameFromURL_Method1(string Url)
    {
        if (!Url.Contains("://"))
            Url = "http://" + Url;

        return new Uri(Url).Host;
    }

    /*
    ** Method 2 (using string modifiers)
    */
    public static string ExtractDomainNameFromURL_Method2(string Url)
    {
        if (Url.Contains(@"://"))
            Url = Url.Split(new string[] { "://" }, 2, StringSplitOptions.None)[1];

        return Url.Split('/')[0];
    }

    /*
    ** Method 3 (using regular expressions -> slowest)
    */
    public static string ExtractDomainNameFromURL_Method3(string Url)
    {
        return System.Text.RegularExpressions.Regex.Replace(
            Url,
            @"^([a-zA-Z]+:\/\/)?([^\/]+)\/.*?$",
            "$2"
        );
    }

    static void Main()
    {
        // Some example urls:
        string[] Urls = new string[]
        {
        "http://www.somedomain.bg/snippets/csharp/",
        "www.somedomain.bg/snippets/csharp/",
        "http://www.somedomain.bg/",
        "ftp://www.somedomain.bg/",
        "www.somedomain.bg/",
        "https://subdomain.abc.def.somedomain.bg/test.htm"
        };

        // Test all urls with all different methods:
        foreach (string Url in Urls)
        {
            Console.WriteLine("Method 1: {0}", ExtractDomainNameFromURL_Method1(Url));
            Console.WriteLine("Method 2: {0}", ExtractDomainNameFromURL_Method2(Url));
            Console.WriteLine("Method 3: {0}", ExtractDomainNameFromURL_Method3(Url));
        }
    }
}