$a = ' dasasdlad jlalsdasd asdloaim dasd asd adsda d <a href="google.com">asdqwd aoldm aikjqld qw as<a href=\'google2.com\' >d a sd aksudmqid jlasdq d wqd aw al;sd ;<A hReF="gOgOlE3.cOm">askd aksd mpqdio aksldj qd '; print htmlspecialchars($a).'<br><br>'; preg_match_all ("/<a.+?href=[\"'](.+?)[\"']/is", $a , $m); print '<pre>'; var_dump($m[1]); print '</pre>';
dasasdlad jlalsdasd asdloaim dasd asd adsda d <a href="google.com">asdqwd aoldm aikjqld qw as<a href='google2.com' >d a sd aksudmqid jlasdq d wqd aw al;sd ;<A hReF="gOgOlE3.cOm">askd aksd mpqdio aksldj qd array(3) { [0]=> string(10) "google.com" [1]=> string(11) "google2.com" [2]=> string(11) "gOgOlE3.cOm" }