Dear Monks,

In the code snippet below, why isn't $a marked as utf-8? The problem I am having is that my database expects me to send it valid utf8. If the string I'm sending it has wide characters as $b does, then everything is fine. If I send it the data in $a it gets truncated because of invalid utf8. (The connection to the DB socket is raw I guess, and so no automatic conversion to utf8 is done.)

Must I check everything I write to the DB with Encode::is_utf8 and decode anything that isn't marked as utf8?

I have read all the Perl Unicode related docs but haven't reached enlightenment. Any help understanding this issue is greatly appreciated. (This is perl 5.8.6) 

#!/usr/bin/perl

use strict;
use warnings;

use Encode;
use Data::Dumper;
use Test::More qw(no_plan);

binmode(STDOUT, ":utf8"); binmode(STDERR, ":utf8");

my $a = "\x{ae}";
my $b = "\x{ae}\x{2122}";

ok( ! Encode::is_utf8($a), '\x{ae} is not marked as utf-8' );
ok(   Encode::is_utf8($b), '\x{ae}\x{2122} is marked as utf-8' );

ok( length $a == 1, '\x{ae} character length 1' );
ok( length $b == 2, '\x{ae}\x{2122} character length 2' );

ok( do { use bytes; length $a } == 1, '\x{ae} byte length 1' );
ok( do { use bytes; length $b } == 5, '\x{ae}\x{2122} byte length 5');

chop $b;

ok(   Encode::is_utf8($b), '$b still utf-8 after chop' );
ok( length $b == 1, '$b character length 1 after chop' );
ok( do { use bytes; length $b } == 2, '$b byte length 2 after chop' );

is( $a, $b, '$a eq $b after utf8 upgrade of $a' );

my $x = decode('iso-8859-1', $a );
ok(   Encode::is_utf8($b), '$x is utf-8' );
ok( $x eq $b );

Encode::_utf8_off( $b );
Encode::_utf8_off( $x );
ok( $x eq $b );
is( $a, $b, '$a and $b are byte same' );

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In reply to Why does perl not mark variable as utf-8? by Anonymous Monk

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