al_get_path_component man page
al_get_path_component — Allegro 5 API
#include <allegro5/allegro.h> const char *al_get_path_component(const ALLEGRO_PATH *path, int i)
Return the i'th directory component of a path, counting from zero. If the index is negative then count from the right, i.e. -1 refers to the last path component. It is an error to pass an index which is out of bounds.