DOKK / manpages / debian 11 / allegro5-doc / al_get_num_display_modes.3alleg5.en
al_get_num_display_modes(3alleg5) al_get_num_display_modes(3alleg5)

al_get_num_display_modes - Allegro 5 API

#include <allegro5/allegro.h>
int al_get_num_display_modes(void)
    

Get the number of available fullscreen display modes for the current set of display parameters. This will use the values set with al_set_new_display_refresh_rate(3alleg5), and al_set_new_display_flags(3alleg5) to find the number of modes that match. Settings the new display parameters to zero will give a list of all modes for the default driver.

al_get_display_mode(3alleg5)

Allegro reference manual