A limited number of safe native PHP functions may also be used as variable modifiers:
* `abs`
-* `addslashes`
-* `array_diff`
-* `array_fill`
* `array_key_exists`
* `array_keys`
* `array_pop`
-* `array_slice`
* `array_values`
* `base64_decode`
* `base64_encode`
* `basename`
* `ceil`
* `concat`
-* `constant`
* `count`
* `currency`
* `current`
* `date`
* `defined`
-* `doubleval`
* `empty`
* `end`
* `explode`
-* `file_exists`
* `filesize`
* `floatval`
* `floor`
* `function_exists`
* `get_class`
* `gmdate`
-* `hash`
-* `htmlspecialchars`
-* `html_entity_decode`
-* `http_build_query`
* `implode`
* `in_array`
* `is_array`
* `intval`
* `is_subclass_of`
* `isset`
-* `json_encode`
* `key`
-* `lcfirst`
* `ltrim`
* `max`
-* `mb_strpos`
* `mb_strlen`
* `mb_strpos`
* `mb_strtolower`
* `method_exists`
* `microtime`
* `min`
-* `nl2br`
-* `number_format`
-* `parse_url`
* `preg_match`
* `preg_replace`
* `print_r`
* `round`
* `sha1`
* `spl_object_hash`
-* `sprintf`
* `strip_tags`
* `strlen`
-* `strpos`
-* `strtolower`
-* `strtotime`
-* `strtoupper`
* `str_contains`
* `str_ends_with`
-* `str_ireplace`
-* `str_pad`
* `str_repeat`
* `str_replace`
* `str_starts_with`
+* `strtolower`
+* `strtoupper`
* `substr`
* `trim`
* `ucfirst`
-* `uniqid`
-* `urlencode`
* `var_dump`
* `version_compare`
* `wcfDebug`
-* `wordwrap`