| 1 | =head1 NAME
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| 2 |
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| 3 | perlunicode - Unicode support in Perl
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| 4 |
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| 5 | =head1 DESCRIPTION
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| 6 |
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| 7 | =head2 Important Caveats
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| 8 |
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| 9 | Unicode support is an extensive requirement. While Perl does not
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| 10 | implement the Unicode standard or the accompanying technical reports
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| 11 | from cover to cover, Perl does support many Unicode features.
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| 12 |
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| 13 | =over 4
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| 14 |
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| 15 | =item Input and Output Layers
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| 16 |
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| 17 | Perl knows when a filehandle uses Perl's internal Unicode encodings
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| 18 | (UTF-8, or UTF-EBCDIC if in EBCDIC) if the filehandle is opened with
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| 19 | the ":utf8" layer. Other encodings can be converted to Perl's
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| 20 | encoding on input or from Perl's encoding on output by use of the
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| 21 | ":encoding(...)" layer. See L<open>.
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| 22 |
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| 23 | To indicate that Perl source itself is using a particular encoding,
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| 24 | see L<encoding>.
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| 25 |
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| 26 | =item Regular Expressions
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| 27 |
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| 28 | The regular expression compiler produces polymorphic opcodes. That is,
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| 29 | the pattern adapts to the data and automatically switches to the Unicode
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| 30 | character scheme when presented with Unicode data--or instead uses
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| 31 | a traditional byte scheme when presented with byte data.
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| 32 |
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| 33 | =item C<use utf8> still needed to enable UTF-8/UTF-EBCDIC in scripts
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| 34 |
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| 35 | As a compatibility measure, the C<use utf8> pragma must be explicitly
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| 36 | included to enable recognition of UTF-8 in the Perl scripts themselves
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| 37 | (in string or regular expression literals, or in identifier names) on
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| 38 | ASCII-based machines or to recognize UTF-EBCDIC on EBCDIC-based
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| 39 | machines. B<These are the only times when an explicit C<use utf8>
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| 40 | is needed.> See L<utf8>.
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