$string = substr("http://lalala.com/index.php?page=ololo", 7);
echo (); 

$url = parse_url("http://lalala.com/index.php?page=ololo");

print_r($url);

Array
(
    [scheme] => http
    [host] => lalala.com
    [path] => /index.php
    [query] => page=ololo
)

echo $url['host']; // lalala.com

	$url='http://lalalalalalalallalalalalalapizdec.com/admin/?page=ololo';
	$string=substr($url, 7);
	$string2=strpos($string, "/");
	$string=substr($string, 0, $string2);
	echo $url; 
	echo'<br />';
	echo $string;