this prints out 'crap' because is_dir() and is_file() return null instead of a boolean if the filename ends with a ?.

yes, the file in the example is a valid windows filename.

$fullPath = realpath("c:/{}d    % test.txt  {}  _-d??+@?#?&()=~^`?'$?");
if (is_dir($fullPath) == null) echo 'crap';

-fab