[要获取过滤器及其 ID 的列表：]
<?php
$filters = filter_list();
foreach($filters as $filter_name) {
echo $filter_name .": ".filter_id($filter_name) ."<br>";
}
?>
将产生
boolean: 258
float: 259
validate_regexp: 272
validate_url: 273
validate_email: 274
validate_ip: 275
string: 513
stripped: 513
encoded: 514
special_chars: 515
unsafe_raw: 516
email: 517
url: 518
number_int: 519
number_float: 520
magic_quotes: 521
callback: 1024