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Encode::Guess(3pm) | User Contributed Perl Documentation | Encode::Guess(3pm) |
NAME¶
Encode::Guess -- Guesses encoding from dataSYNOPSIS¶
# 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 UTFTo 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. 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 heuristics 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, utf8 and UTF-(16|32) with BOM 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"));
TO DO¶
Encode::Guess does not work on EBCDIC platforms.SEE ALSO¶
Encode, Encode::Encoding2014-10-19 | perl v5.20.2 |