al_ustr_rfind_chr - Allegro 5 API

       Search  for  the  encoding of code point c in us backwards from byte offset end_pos (exclusive).  Returns
       the position where it is found or -1 if it is not found.

       al_ustr_rfind_chr - Allegro 5 API

al_ustr_find_chr(3alleg5)

Allegro reference manual                                                              al_ustr_rfind_chr(3alleg5)

              #include <allegro5/allegro.h>

              int al_ustr_rfind_chr(const ALLEGRO_USTR *us, int end_pos, int32_t c)