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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 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.

   # 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 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

Index for Section 3

Alphabetical listing for E

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