al_get_display_mode - Man Page

#include <allegro5/allegro.h>

ALLEGRO_DISPLAY_MODE *al_get_display_mode(int index, ALLEGRO_DISPLAY_MODE *mode)

Retrieves a fullscreen mode. Display parameters should not be changed between a call of al_get_num_display_modes(3) and al_get_display_mode(3). index must be between 0 and the number returned from al_get_num_display_modes-1. mode must be an allocated ALLEGRO_DISPLAY_MODE structure. This function will return NULL on failure, and the mode parameter that was passed in on success.

ALLEGRO_DISPLAY_MODE(3), al_get_num_display_modes(3)

al_get_num_display_modes(3), ALLEGRO_DISPLAY_MODE(3), al_set_new_display_refresh_rate(3).