Encode::Guess(3) User Contributed Perl Documentation 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 $enc = guessencoding($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 (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->setsuspects
           You can also change the internal suspects list via "setsuspects"
           method.

             use Encode::Guess;
             Encode::Guess->setsuspects(qw/euc-jp shiftjis 7bit-jis/);

       Encode::Guess->addsuspects
           Or you can use "addsuspects" method.  The difference is that
           "setsuspects" flushes the current suspects list while
           "addsuspects" adds.

             use Encode::Guess;
             Encode::Guess->addsuspects(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->addsuspects(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);

       guessencoding($data, [, list of suspects])
           You can also try "guessencoding" 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 $decoder = guessencoding($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 $decoder = guessencoding($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 $decoder = guessencoding($data, 'latin1');
             # definitely NOT ok
             my $decoder = guessencoding($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 $decoder
                = guessencoding($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 $decoder =
             guessencoding($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 $decoder = guessencoding($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 v5.16.3                      2013-04-29                  Encode::Guess(3)