$re = '/^(?=(?:[^\n\p{L}]*\p{L}){4}[^\n\p{L}]*$)(?=(?:[^\n\p{N}]*\p{N}){5,6}[^\n\p{N}]*$)(?=(?:[^\n@]*@){3}[^\n@]*$)[\p{L}\p{N} @]+$/m';
$str = '@uuu111
@@@uuug11135
@@@uu1ug1113
@@@uu1ug11134
@@uu1ug11134
@@@uu1ug111f434';
preg_match_all($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