NAME

utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code

SYNOPSIS

    use utf8;
    no utf8;

DESCRIPTION

WARNING: The implementation of Unicode support in Perl is incomplete. See perlunicode for the exact details.

The use utf8 pragma tells the Perl parser to allow UTF-8 in the program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based platforms). The no utf8 pragma tells Perl to switch back to treating the source text as literal bytes in the current lexical scope.

This pragma is primarily a compatibility device. Perl versions earlier than 5.6 allowed arbitrary bytes in source code, whereas in future we would like to standardize on the UTF-8 encoding for source text. Until UTF-8 becomes the default format for source text, this pragma should be used to recognize UTF-8 in the source. When UTF-8 becomes the standard source format, this pragma will effectively become a no-op. For convenience in what follows the term UTF-X is used to refer to UTF-8 on ASCII and ISO Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.

Enabling the utf8 pragma has the following effects:

• Bytes in the source text that have their high-bit set will be treated as being part of a literal UTF-8 character. This includes most literals such as identifiers, string constants, constant regular expression patterns and package names. On EBCDIC platforms, characters in the C1 control group and the Latin 1 character set are treated as being part of a literal UTF-EBCDIC character.

• In the absence of inputs marked as UTF-X, regular expressions within the scope of this pragma will default to using character semantics instead of byte semantics.

      @bytes_or_chars = split //, $data;  # may split to bytes if data
                                          # $data isn't UTF-X
      {
          use utf8;                       # force char semantics
          @chars = split //, $data;       # splits characters
      }

Utility functions

The following functions are defined in the utf8:: package by the perl core.

• $num_octets = utf8::upgrade($string);

  Converts internal representation of string to the perls internal UTF-X form. Returns the number of octets necessary to represent the string as UTF-X.

• utf8::downgrade($string[, CHECK])

  Converts internal representation of string to be un-encoded bytes.

• utf8::encode($string)

  Converts (in-place) $string from logical characters to octet sequence representing it in perl's UTF-X encoding.

• $flag = utf8::decode($string)

  Attempts to convert $string in-place from perl's UTF-X encoding into logical characters.

SEE ALSO

perlunicode, bytes