Directories
PHP Manual

Predefined Constants

DIRECTORY_SEPARATOR (string)
PATH_SEPARATOR (string)
Semicolon on Windows, colon otherwise.
SCANDIR_SORT_ASCENDING (integer)
Available since PHP 5.4.0.
SCANDIR_SORT_DESCENDING (integer)
Available since PHP 5.4.0.
SCANDIR_SORT_NONE (integer)
Available since PHP 5.4.0.

Directories
PHP Manual