desktop_color_depth - Finds out the desktop color depth. Allegro game programming library.

       Finds  out  the currently selected desktop color depth. You can use this information to make your program
       use the same color depth as the desktop, which will likely make it run faster because the graphic  driver
       won't be doing unnecessary color conversions behind your back.

       Under  some  OSes,  switching  to  a full screen graphics mode may automatically change the desktop color
       depth. You have, therefore, to call this function before setting any graphics mode in order  to  retrieve
       the real desktop color depth. Example:

          allegro_init();
          ...
          if ((depth = desktop_color_depth()) != 0) {
             set_color_depth(depth);
          }

       desktop_color_depth - Finds out the desktop color depth. Allegro game programming library.

       Returns the color depth or zero on platforms where this information is not available or does not apply.

get_desktop_resolution(3alleg4), set_color_depth(3alleg4), set_gfx_mode(3alleg4)

Allegro                                           version 4.4.3                     desktop_color_depth(3alleg4)

#include<allegro.h>intdesktop_color_depth();