al_ustr_insert_chr - Allegro 5 API

       Insert a code point into us beginning at byte offset pos.  pos cannot be less than 0.  If pos is past the
       end of us then the space between the end of the string and pos will be padded with NUL ('\0') bytes.

       Returns the number of bytes inserted, or 0 on error.

       al_ustr_insert_chr - Allegro 5 API

al_ustr_insert(3alleg5), al_ustr_insert_cstr(3alleg5)

Allegro reference manual                                                             al_ustr_insert_chr(3alleg5)

              #include <allegro5/allegro.h>

              size_t al_ustr_insert_chr(ALLEGRO_USTR *us, int pos, int32_t c)