al_get_path_drive - Allegro 5 API

       Return the drive letter on a path, or the empty string if there is none.

       The  “drive letter” is only used on Windows, and is usually a string like “c:”, but may be something like
       “\\Computer Name” in the case of UNC (Uniform Naming Convention) syntax.

Allegro reference manual                                                              al_get_path_drive(3alleg5)

       al_get_path_drive - Allegro 5 API

              #include <allegro5/allegro.h>

              const char *al_get_path_drive(const ALLEGRO_PATH *path)