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Encode::Guess(3pm) Perl Programmers Reference Guide Encode::Guess(3pm)
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 7bit-jis/);
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 (sus-
pects as follows). The name of suspects can either be canonical names or aliases.
CAVEAT: Unlike UTF-(16│32), BOM in utf8 is NOT AUTOMATICALLY STRIPPED.
# tries all major Japanese Encodings as well
use Encode::Guess qw/euc-jp shiftjis 7bit-jis/;
If the $Encode::Guess::NoUTFAutoGuess variable is set to a true value, no heuris-
tics will be applied to UTF8/16/32, and the result will be limited to the suspects
and "ascii".
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:
* Two or more suspects remain
* No suspects left
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 is eliminated out of suspects list.
ISO-8859 series is just too successful for most cases (because it fills almost
all code points in \x00-\xff).
· Do not mix national standard encodings and the corresponding vendor encodings.
# a very bad idea
my $decoder
= guess_encoding($data, qw/shiftjis MacJapanese cp932/);
The reason is that vendor encoding is usually a superset 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->encodings(":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 v5.8.6 2001-09-21 Encode::Guess(3pm)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
2009-01-10 06:41 @38.103.63.58 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)