PHP function : Get domain (Host to be exact) from any string (with or without pares_url)

getDomain.php

<?php

/**
 * Return (sub)domain from any string (with and without parse_url)
 *
 * @param $domain str
 */
function getDomain($domain) {
    $host = parse_url($domain, PHP_URL_HOST);
    if($host)
        return $host;

    $domain = preg_replace('#[a-z]+://#siU', '', $domain);
    $domain = preg_replace('#(/.*)$#siU', '', $domain);
    return $domain;
}

header("Content-Type:text/plain;charset=utf-8");

$domains = explode(chr(10), 'http://example.com
https://example.com
http://example.com/foo
http://example.com/foo/bar
www.example.com
example.com
foo.example.com
www.foo.example.com
foo.bar.example.com
http://foo.bar.example.com/foo/bar
example.net/foo/bar');

foreach($domains as $domain) {
    echo $domain.'        '.getDomain($domain).chr(10);
}


/**
 * Return
http://example.com                     example.com
https://example.com                    example.com
http://example.com/foo                 example.com
http://example.com/foo/bar             example.com
www.example.com                        www.example.com
example.com                            example.com
foo.example.com                        foo.example.com
www.foo.example.com                    www.foo.example.com
foo.bar.example.com                    foo.bar.example.com
http://foo.bar.example.com/foo/bar     foo.bar.example.com
example.net/foo/bar                    example.net
*/