Jarkko Hietaniemi > perl-5.8.0 > utf8

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Module Version: 1.00   Source   Latest Release: perl-5.21.2

NAME ^

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

SYNOPSIS ^

    use utf8;
    no utf8;

DESCRIPTION ^

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 effect:

Note that if you have bytes with the eighth bit on in your script (for example embedded Latin-1 in your string literals), use utf8 will be unhappy since the bytes are most probably not well-formed UTF-8. If you want to have such bytes and use utf8, you can disable utf8 until the end the block (or file, if at top level) by no utf8;.

Utility functions

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

utf8::encode is like utf8::upgrade, but the UTF8 flag is cleared. See perlunicode for more on the UTF8 flag and the C API functions sv_utf8_upgrade, sv_utf8_downgrade, sv_utf8_encode, and sv_utf8_decode, which are wrapped by the Perl functions utf8::upgrade, utf8::downgrade, utf8::encode and utf8::decode. Note that in the Perl 5.8.0 implementation the functions utf8::valid, utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are always available, without a require utf8 statement-- this may change in future releases.

BUGS ^

One can have Unicode in identifier names, but not in package/class or subroutine names. While some limited functionality towards this does exist as of Perl 5.8.0, that is more accidental than designed; use of Unicode for the said purposes is unsupported.

One reason of this unfinishedness is its (currently) inherent unportability: since both package names and subroutine names may need to be mapped to file and directory names, the Unicode capability of the filesystem becomes important-- and there unfortunately aren't portable answers.

SEE ALSO ^

perlunicode, bytes

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