Description:
------------
When using the FILTER_SANITIZE_STRING filter on a string with a null byte, the null byte character will be removed.

Could this be added to the documentation?

http://php.net/manual/en/filter.filters.sanitize.php



Test script:
---------------
<?php

$a = array_map('chr', range(0,32));

for($i = 0; $i < 32; $i++) {
        if (strlen($a[$i]) != strlen(filter_var($a[$i], FILTER_SANITIZE_STRING))) {
                echo 'ASCII character '.$i." has been removed from the string\n";
        }
}


Expected result:
----------------
The function removes the null byte, this could be the intended functionality.

The PHP function strip_tags also removes the null byte and it is listed in the documentation.

Additionally when using the filter flag FILTER_FLAG_ENCODE_LOW the return value is instead the encoded version of the null byte &#0;