- var_dump: documentation ( source)
- preg_match: documentation ( source)
- var_export: documentation ( source)
- preg_quote: documentation ( source)
<?php
$kw = " asdsdfsdf \t as ";
$pattern = '/^((?![[:cntrl:]' . preg_quote(',!@%^*()={};~`<>?\|', '/') . ']).)*$/u';
var_dump($pattern);
var_dump(var_export($pattern, true));
var_dump(preg_match($pattern, $kw));