I'm at a loss as to why I'm having this problem. I'm running IIS on Windows 7 for development but have a Linux server for web hosting.

The problem is whenever I use a PHP system function, like `file_exists()` or `move_uploaded_file()`, using a path like `/support/images/flags/countries/` always fails. The support directory is under the root directory of the site. All the documentation I have read seems to state that the path should work. Is this because I use Windows? Even the posts on SO seem to say it should work.

In order to get it to work correctly I have to use a path like `{$_SERVER['DOCUMENT_ROOT']}/support/images/flags/countries`

Can anyone explain why my thinking is wrong?