al_ustr_append - Allegro 5 API

       Append us2 to the end of us1.

       Returns true on success, false on error.

       This function can be used to append an arbitrary buffer:

                ALLEGRO_USTR_INFO info;
                al_ustr_append(us, al_ref_buffer(&info, buf, size));

       al_ustr_append - Allegro 5 API

al_ustr_append_cstr(3alleg5),            al_ustr_append_chr(3alleg5),           al_ustr_appendf(3alleg5),
       al_ustr_vappendf(3alleg5)

Allegro reference manual                                                                 al_ustr_append(3alleg5)

              #include <allegro5/allegro.h>

              bool al_ustr_append(ALLEGRO_USTR *us1, const ALLEGRO_USTR *us2)