remove subdomain from url PHP

Question

I'm cleaning URL from a text file with a PHP script, here's the code right now :

        $file = __DIR__."/url.txt";
        $f = fopen($file, "r");
        $array1 = array();

        while ( $line = fgets($f, 1000) ) {
            $nl = mb_strtolower($line,'UTF-8');
            $array1[] = $nl;
        }


        foreach ($array1 as $value) {
            $value = preg_replace('#^https?://#', '', $value);
            $value = preg_replace('#^www.#', '', $value);

            echo $value."<br>";
        }

So I remove the http:// and www from these urls

Here's the output :

urlnumberone.com
urlnumbertwo.uk
subdomain.urlnumberthree.com
urlnumberfour.com

What I want is to remove subdomain too, and just have urlnumberthree.com

Thanks for your help !

Answer 1

Pure regex solution:

preg_match('#[^\.]+[\.]{1}[^\.]+$#', $value , $matches);
$value = $matches[0]; 

This replaces both of your preg_replace s.

Answer 2

Check occurrences of '.' if they are more than 1, remove the beginning until first dot.