$re = '/0[xX]([0-9a-fA-F]+)\nwtf/ms';
$str = '1616846098450
trying : 16633299966633299966633299
0x4d68c66a4b7ac51f87e22d0e0b70a4ebc7f6286e7834ec3da18c6147f578afe8
wtf
0x848fcea771facf657677f1f3a919ab7e43b1f7d0df95bf8375113c5621e063c2';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php