$re = '/msg-type="(?!(?:JOIN|INFO|TOPIC))[^"]+"/m';
$str = 'msg-type="codePRIVMSGcode"
msg-type="PRIVMSG"
msg-type="PRIVMSGcode"
msg-type="codePRIVMSG"
msg-type="codeJOINcode"
msg-type="JOIN"
msg-type="JOINcode"
msg-type="codeJOIN"
msg-type="codeTOPICcode"
msg-type="codeINFOcode"
msg-type="PRIVMSG"
msg-type="OTHER"
';
preg_match_all($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