al_init - Allegro 5 API

       Like  al_install_system(3alleg5),  but  automatically  passes in the version and uses the atexit function
       visible in the current binary.

              Note: It is typically wrong to call al_init anywhere except the final game binary.  In particular,
              do not call it inside a shared library unless you know what you’re doing.  In those cases,  it  is
              better  to  call  al_install_system  either  with  a  NULL atexit_ptr, or with a pointer to atexit
              provided by the user of this shared library.

       al_init - Allegro 5 API

al_install_system(3alleg5)

Allegro reference manual                                                                        al_init(3alleg5)

              #include <allegro5/allegro.h>

              #define al_init()    (al_install_system(ALLEGRO_VERSION_INT, atexit))