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)