al_get_joystick_active man page
al_get_joystick_active — Allegro 5 API
#include <allegro5/allegro.h> bool al_get_joystick_active(ALLEGRO_JOYSTICK *joy)
Return if the joystick handle is "active", i.e. in the current configuration, the handle represents some physical device plugged into the system. al_get_joystick(3) returns active handles. After reconfiguration, active handles may become inactive, and vice versa.