Error running Allegro on OSX

Question

I ran brew install allegro on OSX

following this tutorial: https://wiki.allegro.cc/index.php?title=Example_ExHello

my code

include <allegro.h>

int main(void) { 
  if (allegro_init() != 0)
     return 1;

  /* set up the keyboard handler */
  install_keyboard(); 

  /* set a graphics mode sized 320x200 */
  if (set_gfx_mode(GFX_AUTODETECT, 320, 200, 0, 0) != 0) {
     if (set_gfx_mode(GFX_SAFE, 320, 200, 0, 0) != 0) {
   set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
   allegro_message("Unable to set any graphic mode\n%s\n", allegro_error);
   return 1;
     }
  }

  /* set the color palette */
  set_palette(desktop_palette);

  /* clear the screen to white */
  clear_to_color(screen, makecol(255, 255, 255));

  /* you don't need to do this, but on some platforms (eg. Windows) things
   * will be drawn more quickly if you always acquire the screen before
   * trying to draw onto it.
   */
  acquire_screen();

  /* write some text to the screen with black letters and transparent background */
  textout_centre_ex(screen, font, "Hello, world!", SCREEN_W/2, SCREEN_H/2, makecol(0,0,0), -1);

  /* you must always release bitmaps before calling any input functions */
  release_screen();

  /* wait for a keypress */
  readkey();

  return 0;
}



1.c:1:1: error: unknown type name 'include'
include <allegro.h>
^
1.c:1:9: error: expected identifier or '('
include <allegro.h>
        ^
2 errors generated.
make: *** [1] Error 1

score 0 · Accepted Answer · answered Mar 10 '17 at 15:00

Presuming that the typo of doing include <allegro.h> was supposed to be #include <allegro.h>, You've installed allegro5 - the API is very different between allegro4 (which this example is from) and allegro5. The display initialization sample program for allegro5 shows some of the differences:

#include <stdio.h>
#include <allegro5/allegro.h>

int main(int argc, char **argv){

   ALLEGRO_DISPLAY *display = NULL;

   if(!al_init()) { // allegro_init in allegro4
      fprintf(stderr, "failed to initialize allegro!\n");
      return -1;
   }

   display = al_create_display(640, 480); // very different to allegro4
   if(!display) {
      fprintf(stderr, "failed to create display!\n");
      return -1;
   }

   al_clear_to_color(al_map_rgb(0,0,0)); // makecol -> al_map_rgb, clear_to_color -> al_clear_to_color

   al_flip_display();

   al_rest(10.0);

   al_destroy_display(display);

   return 0;
}

I built it using:

 c++ -I/usr/local/include allegro_display.cc -o allegro_display -L/usr/local/lib -lallegro -lallegro_main

where the code was in the file allegro_display.cc. Note that I compile using the C++ compiler, because allegro is really a C++ api (and the sample does not work when compiled as C code because there is no proper calling convention for structs in C, whereas there is for C++)

I was mistakenly under the impression allegro was a pure c library. Thank you, this draws a black rectangle window . — quantumpotato, Mar 10 '17 at 17:05
My reasoning on the C vs C++ issue is that when I compiled this example with the c compiler, replacing the `al_map_rgb(0,0,0)` with `al_map_rgb(255,255,255)` the program would crash with a SEGV, which is some form of binary compatibility issue or compiler issue which *seems* to be avoided by using the C++ compiler. — Anya Shenanigans, Mar 10 '17 at 17:40

Error running Allegro on OSX

1 Answers1