al_set_path_filename - Man Page

#include <allegro5/allegro.h>

void al_set_path_filename(ALLEGRO_PATH *path, const char *filename)

Set the optional filename part of the path. The filename may be NULL, which is equivalent to setting the filename to the empty string.

al_set_path_extension(3), al_get_path_filename(3)

al_set_path_extension(3).