use encoding "greek"; # Perl like Greek to you?
use encoding "euc-jp"; # Jperl!
# or you can even do this if your shell supports your native encoding
perl -Mencoding=latin2 -e '...' # Feeling centrally European?
perl -Mencoding=euc-kr -e '...' # Or Korean?
# more control
# A simple euc-cn => utf-8 converter
use encoding "euc-cn", STDOUT => "utf8"; while(<>){print};
# "no encoding;" supported (but not scoped!)
no encoding;
# an alternate way, Filter
use encoding "euc-jp", Filter=>1;
# now you can use kanji identifiers -- in euc-jp!
# switch on locale -
# note that this probably means that unless you have a complete control
# over the environments the application is ever going to be run, you should
# NOT use the feature of encoding pragma allowing you to write your script
# in any recognized encoding because changing locale settings will wreck
# the script; you can of course still use the other features of the pragma.
use encoding ':locale';
Rewind to the future: starting from perl 5.8.0 with the encoding pragma, you can write your script in any encoding you like (so long as the "Encode" module supports it) and still enjoy Unicode support. This pragma achieves that by doing the following:
my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
#<-char-><-char-> # 4 octets
s/\bCamel\b/$Rakuda/;
And with "use encoding "euc-jp"" in effect, it is the same thing as the code in UTF-8:
my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters
s/\bCamel\b/$Rakuda/;
use encoding "euc-jp"; my $message = "Camel is the symbol of perl.\n"; my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji $message =~ s/\bCamel\b/$Rakuda/; print $message;
Will print ``\xF1\xD1\xF1\xCC is the symbol of perl.\n'', not ``\x{99F1}\x{99DD} is the symbol of perl.\n''.
You can override this by giving extra arguments; see below.
The encoding pragma changes this to use the specified encoding instead. For example:
use encoding 'utf8';
my $string = chr(20000); # a Unicode string
utf8::encode($string); # now it's a UTF-8 encoded byte string
# concatenate with another Unicode string
print length($string . chr(20000));
Will print 2, because $string is upgraded as UTF-8. Without "use encoding 'utf8';", it will print 4 instead, since $string is three octets when interpreted as Latin-1.
This pragma affects utf8::upgrade, but not utf8::downgrade.
This pragma affects utf8::upgrade, but not utf8::downgrade.
This pragma affects utf8::upgrade, but not utf8::downgrade.
Note that STDERR WILL NOT be changed.
Also note that non-STD file handles remain unaffected. Use "use open" or "binmode" to change layers of those.
If no encoding is specified, the environment variable PERL_ENCODING is consulted. If no encoding can be found, the error "Unknown encoding 'ENCNAME'" will be thrown.
When ${^UNICODE} exists and non-zero, these options will completely ignored. ${^UNICODE} is a variable introduced in perl 5.8.1. See perlrun see ``${^UNICODE}'' in perlvar and ``-C'' in perlrun for details (perl 5.8.1 and later).
What does this mean? Your source code behaves as if it is written in UTF-8 with 'use utf8' in effect. So even if your editor only supports Shift_JIS, for example, you can still try examples in Chapter 15 of "Programming Perl, 3rd Ed.". For instance, you can use UTF-8 identifiers.
This option is significantly slower and (as of this writing) non-ASCII identifiers are not very stable WITHOUT this option and with the source code written in UTF-8.
By the same reason, the use this pragma inside modules is also discouraged (though not as strongly discouraged as the case above. See below).
If you still have to write a module with this pragma, be very careful of the load order. See the codes below;
# called module package Module_IN_BAR; use encoding "bar"; # stuff in "bar" encoding here 1; # caller script use encoding "foo" use Module_IN_BAR; # surprise! use encoding "bar" is in effect.
The best way to avoid this oddity is to use this pragma RIGHT AFTER other modules are loaded. i.e.
use Module_IN_BAR; use encoding "foo";
\xDF\x{100}
the data is assumed to be in (Latin 1 and) Unicode, not in your native encoding. In other words, this will match in ``greek'':
"\xDF" =~ /\x{3af}/
but this will not
"\xDF\x{100}" =~ /\x{3af}\x{100}/
since the "\xDF" (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on the left will not be upgraded to "\x{3af}" (Unicode GREEK SMALL LETTER IOTA WITH TONOS) because of the "\x{100}" on the left. You should not be mixing your legacy data and Unicode in the same string.
This pragma also affects encoding of the 0x80..0xFF code point range: normally characters in that range are left as eight-bit bytes (unless they are combined with characters with code points 0x100 or larger, in which case all characters need to become UTF-8 encoded), but if the "encoding" pragma is present, even the 0x80..0xFF range always gets UTF-8 encoded.
After all, the best thing about this pragma is that you don't have to resort to \x{....} just to spell your name in a native encoding. So feel free to put your strings in your encoding in quotes and regexes.
use encoding 'euc-jp'; #.... $kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/; # -------- -------- -------- --------
Does not work as
$kana =~ tr/\x{3041}-\x{3093}/\x{30a1}-\x{30f3}/;
utf8 euc-jp charnames::viacode()
-----------------------------------------
\x{3041} \xA4\xA1 HIRAGANA LETTER SMALL A
\x{3093} \xA4\xF3 HIRAGANA LETTER N
\x{30a1} \xA5\xA1 KATAKANA LETTER SMALL A
\x{30f3} \xA5\xF3 KATAKANA LETTER N
This counterintuitive behavior has been fixed in perl 5.8.1.
In perl 5.8.0, you can work around as follows;
use encoding 'euc-jp';
# ....
eval qq{ \$kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/ };
Note the "tr//" expression is surrounded by "qq{}". The idea behind is the same as classic idiom that makes "tr///" 'interpolate'.
tr/$from/$to/; # wrong!
eval qq{ tr/$from/$to/ }; # workaround.
Nevertheless, in case of encoding pragma even "q//" is affected so "tr///" not being decoded was obviously against the will of Perl5 Porters so it has been fixed in Perl 5.8.1 or later.
use encoding "iso 8859-7";
# \xDF in ISO 8859-7 (Greek) is \x{3af} in Unicode.
$a = "\xDF";
$b = "\x{100}";
printf "%#x\n", ord($a); # will print 0x3af, not 0xdf
$c = $a . $b;
# $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".
# chr() is affected, and ...
print "mega\n" if ord(chr(0xdf)) == 0x3af;
# ... ord() is affected by the encoding pragma ...
print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;
# ... as are eq and cmp ...
print "peta\n" if "\x{3af}" eq pack("C", 0xdf);
print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0;
# ... but pack/unpack C are not affected, in case you still
# want to go back to your native encoding
print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;
# Save this one in utf8 # replace *non-ascii* with a non-ascii string my $camel; format STDOUT = *non-ascii*@>>>>>>> $camel . $camel = "*non-ascii*"; binmode(STDOUT=>':encoding(utf8)'); # bang! write; # funny print $camel, "\n"; # fine
Without binmode this happens to work but without binmode, print() fails instead of write().
At any rate, the very use of format is questionable when it comes to unicode characters since you have to consider such things as character width (i.e. double-width for ideographs) and directions (i.e. BIDI for Arabic and Hebrew).
If your locale environment variables (LC_ALL, LC_CTYPE, LANG) contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching), the default encoding of your STDIN, STDOUT, and STDERR, and of any subsequent file open, is UTF-8.
The ":locale" subpragma was implemented in 2.01, or Perl 5.8.6.
Ch. 15 of "Programming Perl (3rd Edition)" by Larry Wall, Tom Christiansen, Jon Orwant; O'Reilly & Associates; ISBN 0-596-00027-8