SCREEN_W, SCREEN_H - Global define to obtain the size of the screen. Allegro game programming library.

       Global  defines  that  return  the  width  and  height  of the screen, or zero if the screen has not been
       initialised yet. Example:

          char buf[100];
          ...
          uszprintf(buf, sizeof(buf),
                    "The screen size is %d x %d pixels",
                    SCREEN_W, SCREEN_H);

       SCREEN_W, SCREEN_H - Global define to obtain the size of the screen. Allegro game programming library.

screen(3alleg4), set_gfx_mode(3alleg4), VIRTUAL_W(3alleg4), VIRTUAL_H(3alleg4)

Allegro                                           version 4.4.3                                SCREEN_W(3alleg4)

#include<allegro.h>#defineSCREEN_W;#defineSCREEN_H;