$re = '/(?<!!)\[(?=[^\]]*[a-z])([a-zA-Z_]+[\w]+)\]/m';
$str = '<?php
$options[$list[_capture_me]][]=array($list[_captureme],$list[_capture_me]);
$option_names[$list[_capture_me]]=$list[_captureme];
$product_name=$list[capture_me];
$product_name=$list[0];
$product_name=$list[DONTCAPTUREME];
$product_name=$list[CapTureMe];
$product_name=$list[CapTurEME];
$actionKey = $get[DONT_CAPTURE_ME];
if(array_key_exists(DONT_CAPTURE_ME,$get)) {
$actionKey = $get[DONT_CAPTURE_ME];
if(array_key_exists($actionKey,$this->arrPageActions)){
$this->arrAllTemplatesAndAttributes[$templateID][captureme][\'Capture_Me\'][$res[option_values_id]] = $res[DONT_CAPTURE_ME];
$old_faq_id.="$result[faq_id]&";
$result[\'toc\']="<b><a href=$PHP_SELF#$result[faq_id]>$result[\'question\']</a></b>";}
$result[\'toc\']="<b><a href=$PHP_SELF#$result[faq_id]>$result[QUESTION]</a></b>";}
$login_groups_id = $check_admin[login_groups_id];
?>
<!--[if lt IE 7]> <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
function check_input(field_name, field_size, message) {
if ($elements[capture_me] && (form.elements[dont_capture].type != "hidden") && $form.elements[capture_me]) {
var field_value = form.elements[dontcapure].value;
var field_value = $form.elements[capureme].value;
if (field_value == \'\' || field_value.length < field_size) {
error_message = error_message + "* " + message + "\\n";
error = true;
}
}
}';
$subst = "['\1']";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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