al_utf8_encode - Allegro 5 API

       Encode  the  specified  code point to UTF-8 into the buffer s.  The buffer must have enough space to hold
       the encoding, which takes between 1 and 4 bytes.  This routine will refuse to encode  code  points  above
       0x10FFFF.

       Returns the number of bytes written, which is the same as that returned by al_utf8_width(3alleg5).

       al_utf8_encode - Allegro 5 API

al_utf16_encode(3alleg5)

Allegro reference manual                                                                 al_utf8_encode(3alleg5)

              #include <allegro5/allegro.h>

              size_t al_utf8_encode(char s[], int32_t c)