Question

What flags do I need to add to g++ in order to compile code using allegro 5? I tried

g++ allegro5test.cpp -o allegro5test `allegro-config --libs`

but that is not working. I’m using ubuntu 11.04. I installed allegro 5 using the instructions at http://wiki.allegro.cc/index.php?title=Install_Allegro5_From_SVN/Linux/Debian

I tried:

g++ allegro5test.cpp -o allegro5test `allegro-config --cflags --libs`

And it also gives a bunch of undefined errors, like: undefined reference to `al_install_system’

allegro-config --cflags --libs outputs:

-I/usr/local/include
-L/usr/local/lib -lalleg

Answer 1

So you successfully installed allegro5 on your system from the SVN. One thing you should know is that this build doesn’t come with allegro-config. If you have it on your system it means you have previously installed allegro4.

allegro5 brings many changes, including different initialization procedures, library and function names.

Here’s a hello world application for new version:

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

int main(int argc, char **argv)
{
   ALLEGRO_DISPLAY *display = NULL;

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

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

   al_clear_to_color(al_map_rgb(0,0,0));
   al_flip_display();
   al_rest(10.0);
   al_destroy_display(display);
   return 0;
}

Notice how the command to compile this application refers to another include directory and library names, which are different from the previous version of allegro:

g++ hello.cpp -o hello -I/usr/include/allegro5 -L/usr/lib -lallegro