This is a very simple function that will run htmlspecialchars() on every value in an array. The function is recursive (calls itself) so even if it holds nested arrays it will still work.

For example:

Would become:
function htmlspecial_array(&$variable) {
foreach ($variable as &$value) {
if (!is_array($value)) { $value = htmlspecialchars($value); }
else { htmlspecial_array($value); }
}
}