TIMTOWTDI...
use warnings;
use strict;
use Test::More tests=>12;
my $in = "\N{U+CF} \N{U+2764} \N{U+1F42A}";
is utf8cut($in, 11), "\N{U+CF} \N{U+2764} \N{U+1F42A}";
is utf8cut($in, $_), "\N{U+CF} \N{U+2764} " for 10,9,8,7;
is utf8cut($in, 6), "\N{U+CF} \N{U+2764}";
is utf8cut($in, $_), "\N{U+CF} " for 5,4,3;
is utf8cut($in, 2), "\N{U+CF}";
is utf8cut($in, $_), "" for 1,0;
sub utf8cut {
my ($str, $bytelen) = @_;
utf8::encode($str);
$str = substr $str, 0, $bytelen;
$str =~ s/(?: [\xC0-\xDF] | [\xE0-\xEF] [\x80-\xBF]?
| [\xF0-\xF7] [\x80-\xBF]{0,2} )\z//x;
utf8::decode($str);
return $str;
}
Updates 1 & 2: As per replies, fixed by removing the code which did special handling when !utf8::is_utf8($str) (and the corresponding tests), which I had originally added to the code as an ill-conceived afterthought.