$re = '/^!(\S+?)(?:(H\d+)|(E\d+)){0,2}$/m';
$str = '!attackH5E4
=> (attack, H5, E4)
!attackE4H5
=> (attack, H5, E4)
!HHHHHHH5
=> (HHHHHH, H5, null)
!HHHHHHH5E4
=> (HHHHHH, H5, E4)
!HHHHHHH5E4
=> (HHHHHH, H5, E4)
!HHHHHHH5E4
=> (HHHHHH, H5, E4)';
preg_match_all($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