PHP regular problem, I want to match and split where (rn) appears twice

<code>$str = "fhd\r\n\r\nfdfk\r\n\r\nuuuuu";
$data = preg_split("(\r\n){2}", $str, -1);
print_r($data);
</code>

Result:

Reply content:

<code>$str = "fhd\r\n\r\nfdfk\r\n\r\nuuuuu";
$data = preg_split("(\r\n){2}", $str, -1);
print_r($data);
</code>

Result:

<code>    $str = "fhd\r\n\r\nfdfk\r\n\r\nuuuuu";
    $data = preg_split("/(\r\n){2}/", $str, -1);
    print_r($data);</code>