= utfbytes : compute UTF length of complete Unicode characters in a UTF byte sequence

    include "sys.m";
    sys := load Sys Sys->PATH;

    utfbytes: fn(buf: array of byte, n: int): int;

Utfbytes examines the n-byte UTF sequence in buf and  returns
the number of bytes representing complete Unicode characters.
The value will be less than n when the region inspected  ends
with an incomplete UTF sequence.

== diagnostic
A  bounds  check error results if n exceeds the length of the
array.

== see ALSO
sys-intro(2), sys-byte2char(2), utf(6)