encode::guess(3)

NAME

Encode::Guess -- Guesses encoding from data

SYNOPSIS

# if you are sure $data won't contain anything bogus
use Encode;
use Encode::Guess qw/euc-jp shiftjis 7bit-jis/;
my $utf8 = decode("Guess", $data);
my $data =  encode("Guess",  $utf8);    #  this  doesn't
work!
# more elaborate way
use Encode::Guess,
my $enc = guess_encoding($data, qw/euc-jp shiftjis 7bitjis/);
ref($enc) or die "Can't guess: $enc"; # trap error  this
way
$utf8 = $enc->decode($data);
# or
$utf8 = decode($enc->name, $data)

ABSTRACT

Encode::Guess enables you to guess in what encoding a
given data is encoded, or at least tries to.

DESCRIPTION

By default, it checks only ascii, utf8 and UTF-16/32 with
BOM.

use Encode::Guess; # ascii/utf8/BOMed UTF

To use it more practically, you have to give the names of
encodings to check (suspects as follows). The name of suspects can either be canonical names or aliases.

# tries all major Japanese Encodings as well

use Encode::Guess qw/euc-jp shiftjis 7bit-jis/;

Encode::Guess->set_suspects

You can also change the internal suspects list via
"set_suspects" method.

use Encode::Guess;
Encode::Guess->set_suspects(qw/euc-jp shiftjis 7bit

jis/);

Encode::Guess->add_suspects

Or you can use "add_suspects" method. The difference
is that "set_suspects" flushes the current suspects
list while "add_suspects" adds.

use Encode::Guess;
Encode::Guess->add_suspects(qw/euc-jp shiftjis 7bit

jis/);
# now the suspects are euc-jp,shiftjis,7bit-jis, AND
# euc-kr,euc-cn, and big5-eten
Encode::Guess->add_suspects(qw/euc-kr euc-cn

big5-eten/);

Encode::decode("Guess" ...)

When you are content with suspects list, you can now

my $utf8 = Encode::decode("Guess", $data);

Encode::Guess->guess($data)

But it will croak if Encode::Guess fails to eliminate
all other suspects but the right one or no suspect was
good. So you should instead try this;

my $decoder = Encode::Guess->guess($data);

On success, $decoder is an object that is documented
in Encode::Encoding. So you can now do this;

my $utf8 = $decoder->decode($data);

On failure, $decoder now contains an error message so
the whole thing would be as follows;

my $decoder = Encode::Guess->guess($data);
die $decoder unless ref($decoder);
my $utf8 = $decoder->decode($data);

guess_encoding($data, [, list of suspects])

You can also try "guess_encoding" function which is
exported by default. It takes $data to check and it
also takes the list of suspects by option. The
optional suspect list is not reflected to the internal suspects list.

my $decoder = guess_encoding($data, qw/euc-jp euc-kr

euc-cn/);
die $decoder unless ref($decoder);
my $utf8 = $decoder->decode($data);
# check only ascii and utf8
my $decoder = guess_encoding($data);

CAVEATS

· Because of the algorithm used, ISO-8859 series and

other single-byte encodings do not work well unless
either one of ISO-8859 is the only one suspect
(besides ascii and utf8).

use Encode::Guess;
# perhaps ok
my $decoder = guess_encoding($data, 'latin1');
# definitely NOT ok
my $decoder = guess_encoding($data, qw/latin1

greek/);

The reason is that Encode::Guess guesses encoding by
trial and error. It first splits $data into lines and
tries to decode the line for each suspect. It keeps
it going until all but one encoding was eliminated out
of suspects list. ISO-8859 series is just too suc
cessful for most cases (because it fills almost all
code points in 0-).

· Do not mix national standard encodings and the corre

sponding vendor encodings.

# a very bad idea
my $decoder

= guess_encoding($data, qw/shiftjis MacJapanese

cp932/);

The reason is that vendor encoding is usually a super
set of national standard so it becomes too ambiguous
for most cases.

· On the other hand, mixing various national standard

encodings automagically works unless $data is too
short to allow for guessing.

# This is ok if $data is long enough
my $decoder =

guess_encoding($data, qw/euc-cn

euc-jp shiftjis 7bit-jis
euc-kr
big5-eten/);

· DO NOT PUT TOO MANY SUSPECTS! Don't you try something

like this!

my $decoder = guess_encoding($data,

Encode->encod

ings(":all"));

It is, after all, just a guess. You should alway be
explicit when it comes to encodings. But there are some,
especially Japanese, environment that guess-coding is a
must. Use this module with care.

TO DO

Encode::Guess does not work on EBCDIC platforms.

SEE ALSO

Encode, Encode::Encoding

perl v5.8.0 2002-06-01 Encode::Guess(3)