# phpman > man > Encode::Guess

## NAME
    [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown) -- Guesses encoding from data

## SYNOPSIS
      # if you are sure $data won't contain anything bogus

      use Encode;
      use [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown);
      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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown); # 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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown) qw/euc-jp shiftjis 7bit-jis/;

    If the $[Encode::Guess::NoUTFAutoGuess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess%3A%3ANoUTFAutoGuess/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->set_suspects
        You can also change the internal suspects list via "set_suspects" method.

          use [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown);
          [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->set_suspects(qw/euc-jp shiftjis 7bit-jis/);

    [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown);
          [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->add_suspects(qw/euc-kr euc-cn big5-eten/);

    [Encode::decode](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3Adecode/markdown)("Guess" ...)
        When you are content with suspects list, you can now

          my $utf8 = [Encode::decode](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3Adecode/markdown)("Guess", $data);

    [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->guess($data)
        But it will croak if:

        *   Two or more suspects remain

        *   No suspects left

        So you should instead try this;

          my $decoder = [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->guess($data);

        On success, $decoder is an object that is documented in [Encode::Encoding](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AEncoding/markdown). 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 $decoder = [Encode::Guess](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown)->guess($data);
          die $decoder unless ref($decoder);
          my $utf8 = $decoder->decode($data);

### guess_encoding
        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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown);
          # 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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AGuess/markdown) does not work on EBCDIC platforms.

## SEE ALSO
    Encode, [Encode::Encoding](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3AEncoding/markdown)