Remove empty subfolders with PHP

Question

I am working on a PHP function that will recursively remove all sub-folders that contain no files starting from a given absolute path.

Here is the code developed so

Answer 1

This line

$ret = $ret ? $ret : $res;

Could be made a little more readable:

$ret = $ret || $res;

Or if PHP has the bitwise operator:

$ret |= $res;