@deftypefun {int} {stringprep_unichar_to_utf8} (uint32_t @var{c}, char * @var{outbuf}) @var{c}: a ISO10646 character code @var{outbuf}: output buffer, must have at least 6 bytes of space. If @code{NULL}, the length will be computed and returned and nothing will be written to @code{outbuf}. Converts a single character to UTF-8. @strong{Return value:} number of bytes written. @end deftypefun