palette_color - Maps palette indexes into the current pixel format colors. Allegro game programming

       Table mapping palette index colors (0-255) into whatever pixel  format  is  being  used  by  the  current
       display mode. In a 256-color mode this just maps onto the array index. In truecolor modes it looks up the
       specified  entry  in  the  current palette, and converts that RGB value into the appropriate packed pixel
       format. Example:

          set_color_depth(32);
          ...
          set_palette(desktop_palette);
          /* Put a pixel with the color 2 (green) of the palette */
          putpixel(screen, 100, 100, palette_color[2]);

       palette_color  -  Maps  palette  indexes  into  the current pixel format colors. Allegro game programming
       library.

set_palette(3alleg4), makecol(3alleg4), set_color_depth(3alleg4)

Allegro                                           version 4.4.3                           palette_color(3alleg4)

#include<allegro.h>externintpalette_color[256];