$re = '/^(?:[\da-z]+|[\dA-Z]+)$/m';
$str = 'TY5TF45TF463CHB7437R
ecrx3yt4cx345748bnc7547
745367456475647378563745
hdgfsdgfsdjfgshdgshdgf
DHFGSDHGFSHDGFHSGFHSDFH
sshd434gfhdghHSDGFH324234SDFHSG
SDASGDASDhghgshdfsh
dhf hsh-d-f-837_483@^%f#@^#2482
';
preg_match_all($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