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perllocale: Unicode has changed their data; fix references
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1=encoding utf8
2
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3=head1 NAME
4
b0c42ed9 5perllocale - Perl locale handling (internationalization and localization)
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6
7=head1 DESCRIPTION
8
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9In the beginning there was ASCII, the "American Standard Code for
10Information Interchange", which works quite well for Americans with
11their English alphabet and dollar-denominated currency. But it doesn't
12work so well even for other English speakers, who may use different
13currencies, such as the pound sterling (as the symbol for that currency
14is not in ASCII); and it's hopelessly inadequate for many of the
15thousands of the world's other languages.
16
17To address these deficiencies, the concept of locales was invented
18(formally the ISO C, XPG4, POSIX 1.c "locale system"). And applications
19were and are being written that use the locale mechanism. The process of
20making such an application take account of its users' preferences in
21these kinds of matters is called B<internationalization> (often
22abbreviated as B<i18n>); telling such an application about a particular
23set of preferences is known as B<localization> (B<l10n>).
24
39332f68 25Perl has been extended to support the locale system. This
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26is controlled per application by using one pragma, one function call,
27and several environment variables.
28
29Unfortunately, there are quite a few deficiencies with the design (and
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30often, the implementations) of locales. Unicode was invented (see
31L<perlunitut> for an introduction to that) in part to address these
32design deficiencies, and nowadays, there is a series of "UTF-8
33locales", based on Unicode. These are locales whose character set is
34Unicode, encoded in UTF-8. Starting in v5.20, Perl fully supports
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35UTF-8 locales, except for sorting and string comparisons like C<lt> and
36C<ge>. (Use L<Unicode::Collate> for these.) Perl continues to support
37the old non UTF-8 locales as well. There are currently no UTF-8 locales
38for EBCDIC platforms.
31f05a37 39
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40(Unicode is also creating C<CLDR>, the "Common Locale Data Repository",
41L<http://cldr.unicode.org/> which includes more types of information than
42are available in the POSIX locale system. At the time of this writing,
43there was no CPAN module that provides access to this XML-encoded data.
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44However, it is possible to compute the POSIX locale data from them, and
45earlier CLDR versions had these already extracted for you as UTF-8 locales
46L<http://unicode.org/Public/cldr/2.0.1/>.)
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47
48=head1 WHAT IS A LOCALE
49
50A locale is a set of data that describes various aspects of how various
51communities in the world categorize their world. These categories are
52broken down into the following types (some of which include a brief
53note here):
54
55=over
56
cb88b78e 57=item Category C<LC_NUMERIC>: Numeric formatting
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58
59This indicates how numbers should be formatted for human readability,
60for example the character used as the decimal point.
61
cb88b78e 62=item Category C<LC_MONETARY>: Formatting of monetary amounts
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63
64=for comment
ebc3223b 65The nbsp below makes this look better (though not great)
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66
67E<160>
68
cb88b78e 69=item Category C<LC_TIME>: Date/Time formatting
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70
71=for comment
ebc3223b 72The nbsp below makes this look better (though not great)
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73
74E<160>
75
cb88b78e 76=item Category C<LC_MESSAGES>: Error and other messages
66cbab2c 77
2619d284 78This is used by Perl itself only for accessing operating system error
03c702c5 79messages via L<$!|perlvar/$ERRNO> and L<$^E|perlvar/$EXTENDED_OS_ERROR>.
66cbab2c 80
cb88b78e 81=item Category C<LC_COLLATE>: Collation
66cbab2c 82
76073c88 83This indicates the ordering of letters for comparison and sorting.
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84In Latin alphabets, for example, "b", generally follows "a".
85
cb88b78e 86=item Category C<LC_CTYPE>: Character Types
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87
88This indicates, for example if a character is an uppercase letter.
89
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90=item Other categories
91
92Some platforms have other categories, dealing with such things as
93measurement units and paper sizes. None of these are used directly by
94Perl, but outside operations that Perl interacts with may use
d6ded950 95these. See L</Not within the scope of "use locale"> below.
2619d284 96
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97=back
98
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99More details on the categories used by Perl are given below in L</LOCALE
100CATEGORIES>.
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101
102Together, these categories go a long way towards being able to customize
103a single program to run in many different locations. But there are
104deficiencies, so keep reading.
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105
106=head1 PREPARING TO USE LOCALES
107
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108Perl itself (outside the L<POSIX> module) will not use locales unless
109specifically requested to (but
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110again note that Perl may interact with code that does use them). Even
111if there is such a request, B<all> of the following must be true
b960a36e 112for it to work properly:
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113
114=over 4
115
116=item *
117
118B<Your operating system must support the locale system>. If it does,
39332f68 119you should find that the C<setlocale()> function is a documented part of
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120its C library.
121
122=item *
123
5a964f20 124B<Definitions for locales that you use must be installed>. You, or
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125your system administrator, must make sure that this is the case. The
126available locales, the location in which they are kept, and the manner
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127in which they are installed all vary from system to system. Some systems
128provide only a few, hard-wired locales and do not allow more to be
129added. Others allow you to add "canned" locales provided by the system
130supplier. Still others allow you or the system administrator to define
14280422 131and add arbitrary locales. (You may have to ask your supplier to
5a964f20 132provide canned locales that are not delivered with your operating
14280422 133system.) Read your system documentation for further illumination.
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134
135=item *
136
137B<Perl must believe that the locale system is supported>. If it does,
138C<perl -V:d_setlocale> will say that the value for C<d_setlocale> is
139C<define>.
140
141=back
142
143If you want a Perl application to process and present your data
144according to a particular locale, the application code should include
d6ded950 145the S<C<use locale>> pragma (see L<The "use locale" pragma>) where
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146appropriate, and B<at least one> of the following must be true:
147
148=over 4
149
c052850d 150=item 1
5f05dabc 151
66cbab2c 152B<The locale-determining environment variables (see L</"ENVIRONMENT">)
5a964f20 153must be correctly set up> at the time the application is started, either
ef3087ec 154by yourself or by whomever set up your system account; or
5f05dabc 155
c052850d 156=item 2
5f05dabc 157
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158B<The application must set its own locale> using the method described in
159L<The setlocale function>.
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160
161=back
162
163=head1 USING LOCALES
164
d6ded950 165=head2 The C<"use locale"> pragma
5f05dabc 166
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167WARNING! Do NOT use this pragma in scripts that have multiple
168L<threads|threads> active. The locale is not local to a single thread.
169Another thread may change the locale at any time, which could cause at a
170minimum that a given thread is operating in a locale it isn't expecting
171to be in. On some platforms, segfaults can also occur. The locale
172change need not be explicit; some operations cause perl to change the
173locale itself. You are vulnerable simply by having done a C<"use
174locale">.
175
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176By default, Perl itself (outside the L<POSIX> module)
177ignores the current locale. The S<C<use locale>>
66cbab2c 178pragma tells Perl to use the current locale for some operations.
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179Starting in v5.16, there are optional parameters to this pragma,
180described below, which restrict which operations are affected by it.
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181
182The current locale is set at execution time by
183L<setlocale()|/The setlocale function> described below. If that function
184hasn't yet been called in the course of the program's execution, the
66cbab2c 185current locale is that which was determined by the L</"ENVIRONMENT"> in
ebc3223b 186effect at the start of the program.
dfcc8045 187If there is no valid environment, the current locale is whatever the
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188system default has been set to. On POSIX systems, it is likely, but
189not necessarily, the "C" locale. On Windows, the default is set via the
190computer's S<C<Control Panel-E<gt>Regional and Language Options>> (or its
191current equivalent).
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192
193The operations that are affected by locale are:
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194
195=over 4
196
d6ded950 197=item B<Not within the scope of C<"use locale">>
b960a36e 198
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199Only certain operations originating outside Perl should be affected, as
200follows:
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201
202=over 4
203
204=item *
2619d284 205
663d437a 206The current locale is used when going outside of Perl with
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207operations like L<system()|perlfunc/system LIST> or
208L<qxE<sol>E<sol>|perlop/qxE<sol>STRINGE<sol>>, if those operations are
209locale-sensitive.
210
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211=item *
212
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213Also Perl gives access to various C library functions through the
214L<POSIX> module. Some of those functions are always affected by the
215current locale. For example, C<POSIX::strftime()> uses C<LC_TIME>;
216C<POSIX::strtod()> uses C<LC_NUMERIC>; C<POSIX::strcoll()> and
9accf6df 217C<POSIX::strxfrm()> use C<LC_COLLATE>. All such functions
2619d284 218will behave according to the current underlying locale, even if that
1d2ab946 219locale isn't exposed to Perl space.
2619d284 220
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221=item *
222
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223XS modules for all categories but C<LC_NUMERIC> get the underlying
224locale, and hence any C library functions they call will use that
8a384d3a 225underlying locale. For more discussion, see L<perlxs/CAVEATS>.
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226
227=back
228
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229Note that all C programs (including the perl interpreter, which is
230written in C) always have an underlying locale. That locale is the "C"
231locale unless changed by a call to L<setlocale()|/The setlocale
232function>. When Perl starts up, it changes the underlying locale to the
233one which is indicated by the L</ENVIRONMENT>. When using the L<POSIX>
234module or writing XS code, it is important to keep in mind that the
235underlying locale may be something other than "C", even if the program
236hasn't explicitly changed it.
237
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238=for comment
239The nbsp below makes this look better (though not great)
240
241E<160>
242
243=item B<Lingering effects of C<S<use locale>>>
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244
245Certain Perl operations that are set-up within the scope of a
d6ded950 246C<use locale> retain that effect even outside the scope.
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247These include:
248
249=over 4
250
251=item *
252
253The output format of a L<write()|perlfunc/write> is determined by an
254earlier format declaration (L<perlfunc/format>), so whether or not the
255output is affected by locale is determined by if the C<format()> is
d6ded950 256within the scope of a C<use locale>, not whether the C<write()>
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257is.
258
259=item *
260
261Regular expression patterns can be compiled using
33be4c61 262L<qrE<sol>E<sol>|perlop/qrE<sol>STRINGE<sol>msixpodualn> with actual
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263matching deferred to later. Again, it is whether or not the compilation
264was done within the scope of C<use locale> that determines the match
265behavior, not if the matches are done within such a scope or not.
266
267=back
268
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269=for comment
270The nbsp below makes this look better (though not great)
271
d6ded950 272
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273E<160>
274
d6ded950 275=item B<Under C<"use locale";>>
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276
277=over 4
278
279=item *
280
d6ded950 281All the above operations
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282
283=item *
284
285B<Format declarations> (L<perlfunc/format>) and hence any subsequent
286C<write()>s use C<LC_NUMERIC>.
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287
288=item *
289
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290B<stringification and output> use C<LC_NUMERIC>.
291These include the results of
292C<print()>,
293C<printf()>,
294C<say()>,
295and
296C<sprintf()>.
66cbab2c 297
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298=item *
299
300B<The comparison operators> (C<lt>, C<le>, C<cmp>, C<ge>, and C<gt>) use
39332f68 301C<LC_COLLATE>. C<sort()> is also affected if used without an
5a964f20 302explicit comparison function, because it uses C<cmp> by default.
14280422 303
5a964f20 304B<Note:> C<eq> and C<ne> are unaffected by locale: they always
de108802 305perform a char-by-char comparison of their scalar operands. What's
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306more, if C<cmp> finds that its operands are equal according to the
307collation sequence specified by the current locale, it goes on to
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308perform a char-by-char comparison, and only returns I<0> (equal) if the
309operands are char-for-char identical. If you really want to know whether
5a964f20 310two strings--which C<eq> and C<cmp> may consider different--are equal
14280422 311as far as collation in the locale is concerned, see the discussion in
cb88b78e 312L<Category C<LC_COLLATE>: Collation>.
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313
314=item *
315
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316B<Regular expressions and case-modification functions> (C<uc()>, C<lc()>,
317C<ucfirst()>, and C<lcfirst()>) use C<LC_CTYPE>
5f05dabc 318
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319=item *
320
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321B<The variables L<$!|perlvar/$ERRNO>> (and its synonyms C<$ERRNO> and
322C<$OS_ERROR>) B<and L<$^E|perlvar/$EXTENDED_OS_ERROR>> (and its synonym
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323C<$EXTENDED_OS_ERROR>) when used as strings use C<LC_MESSAGES>.
324
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325=back
326
66cbab2c 327=back
5f05dabc 328
5a964f20 329The default behavior is restored with the S<C<no locale>> pragma, or
ef3087ec 330upon reaching the end of the block enclosing C<use locale>.
3cd61afa 331Note that C<use locale> calls may be
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332nested, and that what is in effect within an inner scope will revert to
333the outer scope's rules at the end of the inner scope.
5f05dabc 334
5a964f20 335The string result of any operation that uses locale
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336information is tainted, as it is possible for a locale to be
337untrustworthy. See L<"SECURITY">.
5f05dabc 338
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339Starting in Perl v5.16 in a very limited way, and more generally in
340v5.22, you can restrict which category or categories are enabled by this
341particular instance of the pragma by adding parameters to it. For
342example,
343
344 use locale qw(:ctype :numeric);
345
346enables locale awareness within its scope of only those operations
347(listed above) that are affected by C<LC_CTYPE> and C<LC_NUMERIC>.
348
349The possible categories are: C<:collate>, C<:ctype>, C<:messages>,
350C<:monetary>, C<:numeric>, C<:time>, and the pseudo category
351C<:characters> (described below).
352
353Thus you can say
354
355 use locale ':messages';
356
357and only L<$!|perlvar/$ERRNO> and L<$^E|perlvar/$EXTENDED_OS_ERROR>
358will be locale aware. Everything else is unaffected.
359
360Since Perl doesn't currently do anything with the C<LC_MONETARY>
361category, specifying C<:monetary> does effectively nothing. Some
362systems have other categories, such as C<LC_PAPER_SIZE>, but Perl
363also doesn't know anything about them, and there is no way to specify
364them in this pragma's arguments.
365
366You can also easily say to use all categories but one, by either, for
367example,
368
369 use locale ':!ctype';
370 use locale ':not_ctype';
371
372both of which mean to enable locale awarness of all categories but
373C<LC_CTYPE>. Only one category argument may be specified in a
374S<C<use locale>> if it is of the negated form.
375
376Prior to v5.22 only one form of the pragma with arguments is available:
377
378 use locale ':not_characters';
379
380(and you have to say C<not_>; you can't use the bang C<!> form). This
381pseudo category is a shorthand for specifying both C<:collate> and
382C<:ctype>. Hence, in the negated form, it is nearly the same thing as
383saying
384
385 use locale qw(:messages :monetary :numeric :time);
386
387We use the term "nearly", because C<:not_characters> also turns on
388S<C<use feature 'unicode_strings'>> within its scope. This form is
389less useful in v5.20 and later, and is described fully in
390L</Unicode and UTF-8>, but briefly, it tells Perl to not use the
391character portions of the locale definition, that is the C<LC_CTYPE> and
392C<LC_COLLATE> categories. Instead it will use the native character set
393(extended by Unicode). When using this parameter, you are responsible
394for getting the external character set translated into the
395native/Unicode one (which it already will be if it is one of the
396increasingly popular UTF-8 locales). There are convenient ways of doing
397this, as described in L</Unicode and UTF-8>.
398
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399=head2 The setlocale function
400
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401WARNING! Do NOT use this function in a L<thread|threads>. The locale
402will change in all other threads at the same time, and should your
403thread get paused by the operating system, and another started, that
404thread will not have the locale it is expecting. On some platforms,
405there can be a race leading to segfaults if two threads call this
406function nearly simultaneously.
407
14280422 408You can switch locales as often as you wish at run time with the
39332f68 409C<POSIX::setlocale()> function:
5f05dabc 410
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411 # Import locale-handling tool set from POSIX module.
412 # This example uses: setlocale -- the function call
413 # LC_CTYPE -- explained below
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414 # (Showing the testing for success/failure of operations is
415 # omitted in these examples to avoid distracting from the main
ebc3223b 416 # point)
6ea81ccf 417
5f05dabc 418 use POSIX qw(locale_h);
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419 use locale;
420 my $old_locale;
5f05dabc 421
14280422 422 # query and save the old locale
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423 $old_locale = setlocale(LC_CTYPE);
424
425 setlocale(LC_CTYPE, "fr_CA.ISO8859-1");
426 # LC_CTYPE now in locale "French, Canada, codeset ISO 8859-1"
427
428 setlocale(LC_CTYPE, "");
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429 # LC_CTYPE now reset to the default defined by the
430 # LC_ALL/LC_CTYPE/LANG environment variables, or to the system
431 # default. See below for documentation.
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432
433 # restore the old locale
434 setlocale(LC_CTYPE, $old_locale);
435
39332f68 436The first argument of C<setlocale()> gives the B<category>, the second the
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437B<locale>. The category tells in what aspect of data processing you
438want to apply locale-specific rules. Category names are discussed in
66cbab2c 439L</LOCALE CATEGORIES> and L</"ENVIRONMENT">. The locale is the name of a
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440collection of customization information corresponding to a particular
441combination of language, country or territory, and codeset. Read on for
442hints on the naming of locales: not all systems name locales as in the
443example.
444
39332f68 445If no second argument is provided and the category is something other
cb88b78e 446than C<LC_ALL>, the function returns a string naming the current locale
502a173a 447for the category. You can use this value as the second argument in a
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448subsequent call to C<setlocale()>, B<but> on some platforms the string
449is opaque, not something that most people would be able to decipher as
450to what locale it means.
502a173a 451
cb88b78e 452If no second argument is provided and the category is C<LC_ALL>, the
502a173a 453result is implementation-dependent. It may be a string of
c052850d 454concatenated locale names (separator also implementation-dependent)
39332f68 455or a single locale name. Please consult your L<setlocale(3)> man page for
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456details.
457
458If a second argument is given and it corresponds to a valid locale,
459the locale for the category is set to that value, and the function
460returns the now-current locale value. You can then use this in yet
39332f68 461another call to C<setlocale()>. (In some implementations, the return
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462value may sometimes differ from the value you gave as the second
463argument--think of it as an alias for the value you gave.)
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464
465As the example shows, if the second argument is an empty string, the
466category's locale is returned to the default specified by the
467corresponding environment variables. Generally, this results in a
5a964f20 468return to the default that was in force when Perl started up: changes
54310121 469to the environment made by the application after startup may or may not
5a964f20 470be noticed, depending on your system's C library.
5f05dabc 471
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472Note that when a form of C<use locale> that doesn't include all
473categories is specified, Perl ignores the excluded categories.
66cbab2c 474
f170b852 475If C<set_locale()> fails for some reason (for example, an attempt to set
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476to a locale unknown to the system), the locale for the category is not
477changed, and the function returns C<undef>.
478
2619d284 479
39332f68 480For further information about the categories, consult L<setlocale(3)>.
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481
482=head2 Finding locales
483
39332f68 484For locales available in your system, consult also L<setlocale(3)> to
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485see whether it leads to the list of available locales (search for the
486I<SEE ALSO> section). If that fails, try the following command lines:
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487
488 locale -a
489
490 nlsinfo
491
492 ls /usr/lib/nls/loc
493
494 ls /usr/lib/locale
495
496 ls /usr/lib/nls
497
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498 ls /usr/share/locale
499
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500and see whether they list something resembling these
501
2bdf8add 502 en_US.ISO8859-1 de_DE.ISO8859-1 ru_RU.ISO8859-5
502a173a 503 en_US.iso88591 de_DE.iso88591 ru_RU.iso88595
2bdf8add 504 en_US de_DE ru_RU
14280422 505 en de ru
2bdf8add
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506 english german russian
507 english.iso88591 german.iso88591 russian.iso88595
502a173a 508 english.roman8 russian.koi8r
5f05dabc 509
39332f68 510Sadly, even though the calling interface for C<setlocale()> has been
528d65ad 511standardized, names of locales and the directories where the
5a964f20 512configuration resides have not been. The basic form of the name is
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513I<language_territory>B<.>I<codeset>, but the latter parts after
514I<language> are not always present. The I<language> and I<country>
515are usually from the standards B<ISO 3166> and B<ISO 639>, the
516two-letter abbreviations for the countries and the languages of the
517world, respectively. The I<codeset> part often mentions some B<ISO
5188859> character set, the Latin codesets. For example, C<ISO 8859-1>
519is the so-called "Western European codeset" that can be used to encode
520most Western European languages adequately. Again, there are several
521ways to write even the name of that one standard. Lamentably.
5f05dabc 522
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523Two special locales are worth particular mention: "C" and "POSIX".
524Currently these are effectively the same locale: the difference is
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525mainly that the first one is defined by the C standard, the second by
526the POSIX standard. They define the B<default locale> in which
14280422 527every program starts in the absence of locale information in its
5a964f20 528environment. (The I<default> default locale, if you will.) Its language
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529is (American) English and its character codeset ASCII or, rarely, a
530superset thereof (such as the "DEC Multinational Character Set
531(DEC-MCS)"). B<Warning>. The C locale delivered by some vendors
532may not actually exactly match what the C standard calls for. So
533beware.
5f05dabc 534
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535B<NOTE>: Not all systems have the "POSIX" locale (not all systems are
536POSIX-conformant), so use "C" when you need explicitly to specify this
537default locale.
5f05dabc 538
3e6e419a
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539=head2 LOCALE PROBLEMS
540
5a964f20 541You may encounter the following warning message at Perl startup:
3e6e419a
JH
542
543 perl: warning: Setting locale failed.
544 perl: warning: Please check that your locale settings:
545 LC_ALL = "En_US",
546 LANG = (unset)
547 are supported and installed on your system.
548 perl: warning: Falling back to the standard locale ("C").
549
cb88b78e 550This means that your locale settings had C<LC_ALL> set to "En_US" and
5a964f20
TC
551LANG exists but has no value. Perl tried to believe you but could not.
552Instead, Perl gave up and fell back to the "C" locale, the default locale
65ebb059
KW
553that is supposed to work no matter what. (On Windows, it first tries
554falling back to the system default locale.) This usually means your
555locale settings were wrong, they mention locales your system has never
556heard of, or the locale installation in your system has problems (for
557example, some system files are broken or missing). There are quick and
558temporary fixes to these problems, as well as more thorough and lasting
559fixes.
3e6e419a 560
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561=head2 Testing for broken locales
562
563If you are building Perl from source, the Perl test suite file
564F<lib/locale.t> can be used to test the locales on your system.
565Setting the environment variable C<PERL_DEBUG_FULL_TEST> to 1
566will cause it to output detailed results. For example, on Linux, you
567could say
568
1d2ab946 569 PERL_DEBUG_FULL_TEST=1 ./perl -T -Ilib lib/locale.t > locale.log 2>&1
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570
571Besides many other tests, it will test every locale it finds on your
572system to see if they conform to the POSIX standard. If any have
573errors, it will include a summary near the end of the output of which
574locales passed all its tests, and which failed, and why.
575
3e6e419a
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576=head2 Temporarily fixing locale problems
577
5a964f20 578The two quickest fixes are either to render Perl silent about any
3e6e419a
JH
579locale inconsistencies or to run Perl under the default locale "C".
580
581Perl's moaning about locale problems can be silenced by setting the
22ff3130 582environment variable C<PERL_BADLANG> to "0" or "".
900bd440
JH
583This method really just sweeps the problem under the carpet: you tell
584Perl to shut up even when Perl sees that something is wrong. Do not
585be surprised if later something locale-dependent misbehaves.
3e6e419a
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586
587Perl can be run under the "C" locale by setting the environment
cb88b78e
KW
588variable C<LC_ALL> to "C". This method is perhaps a bit more civilized
589than the C<PERL_BADLANG> approach, but setting C<LC_ALL> (or
5a964f20
TC
590other locale variables) may affect other programs as well, not just
591Perl. In particular, external programs run from within Perl will see
3e6e419a 592these changes. If you make the new settings permanent (read on), all
f979aebc 593programs you run see the changes. See L<"ENVIRONMENT"> for
5a964f20 594the full list of relevant environment variables and L<USING LOCALES>
e05ffc7d 595for their effects in Perl. Effects in other programs are
cb88b78e 596easily deducible. For example, the variable C<LC_COLLATE> may well affect
b432a672 597your B<sort> program (or whatever the program that arranges "records"
3e6e419a
JH
598alphabetically in your system is called).
599
5a964f20
TC
600You can test out changing these variables temporarily, and if the
601new settings seem to help, put those settings into your shell startup
663d437a 602files. Consult your local documentation for the exact details. For
5a964f20 603Bourne-like shells (B<sh>, B<ksh>, B<bash>, B<zsh>):
3e6e419a
JH
604
605 LC_ALL=en_US.ISO8859-1
606 export LC_ALL
607
5a964f20
TC
608This assumes that we saw the locale "en_US.ISO8859-1" using the commands
609discussed above. We decided to try that instead of the above faulty
610locale "En_US"--and in Cshish shells (B<csh>, B<tcsh>)
3e6e419a
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611
612 setenv LC_ALL en_US.ISO8859-1
c47ff5f1 613
663d437a 614or if you have the "env" application you can do (in any shell)
c406981e
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615
616 env LC_ALL=en_US.ISO8859-1 perl ...
617
5a964f20 618If you do not know what shell you have, consult your local
3e6e419a
JH
619helpdesk or the equivalent.
620
621=head2 Permanently fixing locale problems
622
5a964f20
TC
623The slower but superior fixes are when you may be able to yourself
624fix the misconfiguration of your own environment variables. The
3e6e419a
JH
625mis(sing)configuration of the whole system's locales usually requires
626the help of your friendly system administrator.
627
5a964f20
TC
628First, see earlier in this document about L<Finding locales>. That tells
629how to find which locales are really supported--and more importantly,
630installed--on your system. In our example error message, environment
631variables affecting the locale are listed in the order of decreasing
632importance (and unset variables do not matter). Therefore, having
633LC_ALL set to "En_US" must have been the bad choice, as shown by the
634error message. First try fixing locale settings listed first.
3e6e419a 635
5a964f20
TC
636Second, if using the listed commands you see something B<exactly>
637(prefix matches do not count and case usually counts) like "En_US"
638without the quotes, then you should be okay because you are using a
639locale name that should be installed and available in your system.
4a4eefd0 640In this case, see L<Permanently fixing your system's locale configuration>.
3e6e419a 641
4a4eefd0 642=head2 Permanently fixing your system's locale configuration
3e6e419a 643
5a964f20 644This is when you see something like:
3e6e419a
JH
645
646 perl: warning: Please check that your locale settings:
647 LC_ALL = "En_US",
648 LANG = (unset)
649 are supported and installed on your system.
650
651but then cannot see that "En_US" listed by the above-mentioned
5a964f20
TC
652commands. You may see things like "en_US.ISO8859-1", but that isn't
653the same. In this case, try running under a locale
654that you can list and which somehow matches what you tried. The
3e6e419a 655rules for matching locale names are a bit vague because
e05ffc7d 656standardization is weak in this area. See again the
13a2d996 657L<Finding locales> about general rules.
3e6e419a 658
b687b08b 659=head2 Fixing system locale configuration
3e6e419a 660
5a964f20
TC
661Contact a system administrator (preferably your own) and report the exact
662error message you get, and ask them to read this same documentation you
663are now reading. They should be able to check whether there is something
664wrong with the locale configuration of the system. The L<Finding locales>
665section is unfortunately a bit vague about the exact commands and places
666because these things are not that standardized.
3e6e419a 667
5f05dabc
PP
668=head2 The localeconv function
669
39332f68 670The C<POSIX::localeconv()> function allows you to get particulars of the
14280422 671locale-dependent numeric formatting information specified by the current
a835cd47
KW
672underlying C<LC_NUMERIC> and C<LC_MONETARY> locales (regardless of
673whether called from within the scope of C<S<use locale>> or not). (If
674you just want the name of
39332f68 675the current locale for a particular category, use C<POSIX::setlocale()>
5a964f20 676with a single parameter--see L<The setlocale function>.)
5f05dabc
PP
677
678 use POSIX qw(locale_h);
5f05dabc
PP
679
680 # Get a reference to a hash of locale-dependent info
681 $locale_values = localeconv();
682
683 # Output sorted list of the values
684 for (sort keys %$locale_values) {
14280422 685 printf "%-20s = %s\n", $_, $locale_values->{$_}
5f05dabc
PP
686 }
687
39332f68 688C<localeconv()> takes no arguments, and returns B<a reference to> a hash.
5a964f20 689The keys of this hash are variable names for formatting, such as
502a173a 690C<decimal_point> and C<thousands_sep>. The values are the
cea6626f 691corresponding, er, values. See L<POSIX/localeconv> for a longer
502a173a
JH
692example listing the categories an implementation might be expected to
693provide; some provide more and others fewer. You don't need an
39332f68 694explicit C<use locale>, because C<localeconv()> always observes the
502a173a 695current locale.
5f05dabc 696
5a964f20
TC
697Here's a simple-minded example program that rewrites its command-line
698parameters as integers correctly formatted in the current locale:
5f05dabc 699
ef3087ec
KW
700 use POSIX qw(locale_h);
701
702 # Get some of locale's numeric formatting parameters
703 my ($thousands_sep, $grouping) =
704 @{localeconv()}{'thousands_sep', 'grouping'};
705
706 # Apply defaults if values are missing
707 $thousands_sep = ',' unless $thousands_sep;
708
709 # grouping and mon_grouping are packed lists
710 # of small integers (characters) telling the
711 # grouping (thousand_seps and mon_thousand_seps
712 # being the group dividers) of numbers and
713 # monetary quantities. The integers' meanings:
714 # 255 means no more grouping, 0 means repeat
715 # the previous grouping, 1-254 means use that
716 # as the current grouping. Grouping goes from
717 # right to left (low to high digits). In the
718 # below we cheat slightly by never using anything
719 # else than the first grouping (whatever that is).
720 if ($grouping) {
721 @grouping = unpack("C*", $grouping);
722 } else {
723 @grouping = (3);
724 }
725
726 # Format command line params for current locale
727 for (@ARGV) {
728 $_ = int; # Chop non-integer part
729 1 while
730 s/(\d)(\d{$grouping[0]}($|$thousands_sep))/$1$thousands_sep$2/;
731 print "$_";
732 }
733 print "\n";
5f05dabc 734
03ceeedf
KW
735Note that if the platform doesn't have C<LC_NUMERIC> and/or
736C<LC_MONETARY> available or enabled, the corresponding elements of the
737hash will be missing.
738
74c76037 739=head2 I18N::Langinfo
4bbcc6e8
JH
740
741Another interface for querying locale-dependent information is the
39332f68 742C<I18N::Langinfo::langinfo()> function, available at least in Unix-like
4bbcc6e8
JH
743systems and VMS.
744
39332f68
KW
745The following example will import the C<langinfo()> function itself and
746three constants to be used as arguments to C<langinfo()>: a constant for
74c76037
JH
747the abbreviated first day of the week (the numbering starts from
748Sunday = 1) and two more constants for the affirmative and negative
749answers for a yes/no question in the current locale.
4bbcc6e8 750
74c76037 751 use I18N::Langinfo qw(langinfo ABDAY_1 YESSTR NOSTR);
4bbcc6e8 752
ef3087ec
KW
753 my ($abday_1, $yesstr, $nostr)
754 = map { langinfo } qw(ABDAY_1 YESSTR NOSTR);
4bbcc6e8 755
74c76037 756 print "$abday_1? [$yesstr/$nostr] ";
4bbcc6e8 757
74c76037
JH
758In other words, in the "C" (or English) locale the above will probably
759print something like:
760
e05ffc7d 761 Sun? [yes/no]
4bbcc6e8
JH
762
763See L<I18N::Langinfo> for more information.
764
5f05dabc
PP
765=head1 LOCALE CATEGORIES
766
5a964f20
TC
767The following subsections describe basic locale categories. Beyond these,
768some combination categories allow manipulation of more than one
769basic category at a time. See L<"ENVIRONMENT"> for a discussion of these.
5f05dabc 770
cb88b78e 771=head2 Category C<LC_COLLATE>: Collation
5f05dabc 772
d6ded950
KW
773In the scope of a S<C<use locale>> form that includes collation, Perl
774looks to the C<LC_COLLATE>
5a964f20 775environment variable to determine the application's notions on collation
b4ffc3db
TC
776(ordering) of characters. For example, "b" follows "a" in Latin
777alphabets, but where do "E<aacute>" and "E<aring>" belong? And while
f87fa335 778"color" follows "chocolate" in English, what about in traditional Spanish?
5f05dabc 779
60f0fa02 780The following collations all make sense and you may meet any of them
dbf3c4d7 781if you C<"use locale">.
60f0fa02
JH
782
783 A B C D E a b c d e
35316ca3 784 A a B b C c D d E e
60f0fa02
JH
785 a A b B c C d D e E
786 a b c d e A B C D E
787
f1cbbd6e 788Here is a code snippet to tell what "word"
5a964f20 789characters are in the current locale, in that locale's order:
5f05dabc
PP
790
791 use locale;
35316ca3 792 print +(sort grep /\w/, map { chr } 0..255), "\n";
5f05dabc 793
14280422
DD
794Compare this with the characters that you see and their order if you
795state explicitly that the locale should be ignored:
5f05dabc
PP
796
797 no locale;
35316ca3 798 print +(sort grep /\w/, map { chr } 0..255), "\n";
5f05dabc
PP
799
800This machine-native collation (which is what you get unless S<C<use
801locale>> has appeared earlier in the same block) must be used for
802sorting raw binary data, whereas the locale-dependent collation of the
b0c42ed9 803first example is useful for natural text.
5f05dabc 804
14280422
DD
805As noted in L<USING LOCALES>, C<cmp> compares according to the current
806collation locale when C<use locale> is in effect, but falls back to a
de108802 807char-by-char comparison for strings that the locale says are equal. You
39332f68 808can use C<POSIX::strcoll()> if you don't want this fall-back:
14280422
DD
809
810 use POSIX qw(strcoll);
811 $equal_in_locale =
812 !strcoll("space and case ignored", "SpaceAndCaseIgnored");
813
39332f68 814C<$equal_in_locale> will be true if the collation locale specifies a
5a964f20 815dictionary-like ordering that ignores space characters completely and
9e3a2af8 816which folds case.
14280422 817
dbf3c4d7 818Perl currently only supports single-byte locales for C<LC_COLLATE>. This means
31f05a37
KW
819that a UTF-8 locale likely will just give you machine-native ordering.
820Use L<Unicode::Collate> for the full implementation of the Unicode
821Collation Algorithm.
822
5a964f20 823If you have a single string that you want to check for "equality in
14280422 824locale" against several others, you might think you could gain a little
39332f68 825efficiency by using C<POSIX::strxfrm()> in conjunction with C<eq>:
14280422
DD
826
827 use POSIX qw(strxfrm);
828 $xfrm_string = strxfrm("Mixed-case string");
829 print "locale collation ignores spaces\n"
830 if $xfrm_string eq strxfrm("Mixed-casestring");
831 print "locale collation ignores hyphens\n"
832 if $xfrm_string eq strxfrm("Mixedcase string");
833 print "locale collation ignores case\n"
834 if $xfrm_string eq strxfrm("mixed-case string");
835
39332f68 836C<strxfrm()> takes a string and maps it into a transformed string for use
de108802 837in char-by-char comparisons against other transformed strings during
14280422 838collation. "Under the hood", locale-affected Perl comparison operators
39332f68
KW
839call C<strxfrm()> for both operands, then do a char-by-char
840comparison of the transformed strings. By calling C<strxfrm()> explicitly
14280422 841and using a non locale-affected comparison, the example attempts to save
5a964f20 842a couple of transformations. But in fact, it doesn't save anything: Perl
2ae324a7 843magic (see L<perlguts/Magic Variables>) creates the transformed version of a
5a964f20 844string the first time it's needed in a comparison, then keeps this version around
14280422 845in case it's needed again. An example rewritten the easy way with
e38874e2 846C<cmp> runs just about as fast. It also copes with null characters
39332f68 847embedded in strings; if you call C<strxfrm()> directly, it treats the first
5a964f20
TC
848null it finds as a terminator. don't expect the transformed strings
849it produces to be portable across systems--or even from one revision
39332f68 850of your operating system to the next. In short, don't call C<strxfrm()>
e38874e2 851directly: let Perl do it for you.
14280422 852
5a964f20 853Note: C<use locale> isn't shown in some of these examples because it isn't
dfcc8045
KW
854needed: C<strcoll()> and C<strxfrm()> are POSIX functions
855which use the standard system-supplied C<libc> functions that
856always obey the current C<LC_COLLATE> locale.
5f05dabc 857
cb88b78e 858=head2 Category C<LC_CTYPE>: Character Types
5f05dabc 859
d6ded950
KW
860In the scope of a S<C<use locale>> form that includes C<LC_CTYPE>, Perl
861obeys the C<LC_CTYPE> locale
14280422 862setting. This controls the application's notion of which characters are
ebc3223b
KW
863alphabetic, numeric, punctuation, I<etc>. This affects Perl's C<\w>
864regular expression metanotation,
f1cbbd6e 865which stands for alphanumeric characters--that is, alphabetic,
ebc3223b
KW
866numeric, and the platform's native underscore.
867(Consult L<perlre> for more information about
14280422 868regular expressions.) Thanks to C<LC_CTYPE>, depending on your locale
b4ffc3db
TC
869setting, characters like "E<aelig>", "E<eth>", "E<szlig>", and
870"E<oslash>" may be understood as C<\w> characters.
ebc3223b
KW
871It also affects things like C<\s>, C<\D>, and the POSIX character
872classes, like C<[[:graph:]]>. (See L<perlrecharclass> for more
873information on all these.)
5f05dabc 874
2c268ad5 875The C<LC_CTYPE> locale also provides the map used in transliterating
68dc0745 876characters between lower and uppercase. This affects the case-mapping
663d437a
KW
877functions--C<fc()>, C<lc()>, C<lcfirst()>, C<uc()>, and C<ucfirst()>;
878case-mapping
b9cc4f69
KW
879interpolation with C<\F>, C<\l>, C<\L>, C<\u>, or C<\U> in double-quoted
880strings and C<s///> substitutions; and case-independent regular expression
e38874e2
DD
881pattern matching using the C<i> modifier.
882
31f05a37
KW
883Starting in v5.20, Perl supports UTF-8 locales for C<LC_CTYPE>, but
884otherwise Perl only supports single-byte locales, such as the ISO 8859
885series. This means that wide character locales, for example for Asian
8c6180a9
KW
886languages, are not well-supported. (If the platform has the capability
887for Perl to detect such a locale, starting in Perl v5.22,
888L<Perl will warn, default enabled|warnings/Category Hierarchy>,
889using the C<locale> warning category, whenever such a locale is switched
890into.) The UTF-8 locale support is actually a
31f05a37 891superset of POSIX locales, because it is really full Unicode behavior
13af4fd9
KW
892as if no C<LC_CTYPE> locale were in effect at all (except for tainting;
893see L</SECURITY>). POSIX locales, even UTF-8 ones,
31f05a37
KW
894are lacking certain concepts in Unicode, such as the idea that changing
895the case of a character could expand to be more than one character.
896Perl in a UTF-8 locale, will give you that expansion. Prior to v5.20,
897Perl treated a UTF-8 locale on some platforms like an ISO 8859-1 one,
898with some restrictions, and on other platforms more like the "C" locale.
899For releases v5.16 and v5.18, C<S<use locale 'not_characters>> could be
900used as a workaround for this (see L</Unicode and UTF-8>).
901
5d63e270 902Note that there are quite a few things that are unaffected by the
663d437a
KW
903current locale. Any literal character is the native character for the
904given platform. Hence 'A' means the character at code point 65 on ASCII
905platforms, and 193 on EBCDIC. That may or may not be an 'A' in the
906current locale, if that locale even has an 'A'.
907Similarly, all the escape sequences for particular characters,
5d63e270
KW
908C<\n> for example, always mean the platform's native one. This means,
909for example, that C<\N> in regular expressions (every character
1d2ab946 910but new-line) works on the platform character set.
5d63e270 911
8c6180a9
KW
912Starting in v5.22, Perl will by default warn when switching into a
913locale that redefines any ASCII printable character (plus C<\t> and
84035de0
KW
914C<\n>) into a different class than expected. This is likely to
915happen on modern locales only on EBCDIC platforms, where, for example,
916a CCSID 0037 locale on a CCSID 1047 machine moves C<"[">, but it can
917happen on ASCII platforms with the ISO 646 and other
8c6180a9
KW
9187-bit locales that are essentially obsolete. Things may still work,
919depending on what features of Perl are used by the program. For
920example, in the example from above where C<"|"> becomes a C<\w>, and
921there are no regular expressions where this matters, the program may
922still work properly. The warning lists all the characters that
923it can determine could be adversely affected.
924
14280422
DD
925B<Note:> A broken or malicious C<LC_CTYPE> locale definition may result
926in clearly ineligible characters being considered to be alphanumeric by
e199995e 927your application. For strict matching of (mundane) ASCII letters and
5a964f20 928digits--for example, in command strings--locale-aware applications
e199995e 929should use C<\w> with the C</a> regular expression modifier. See L<"SECURITY">.
5f05dabc 930
fee33030 931=head2 Category C<LC_NUMERIC>: Numeric Formatting
5f05dabc 932
d6ded950
KW
933After a proper C<POSIX::setlocale()> call, and within the scope of
934of a C<use locale> form that includes numerics, Perl obeys the
935C<LC_NUMERIC> locale information, which controls an application's idea
936of how numbers should be formatted for human readability.
b960a36e 937In most implementations the only effect is to
b4ffc3db 938change the character used for the decimal point--perhaps from "." to ",".
b960a36e 939The functions aren't aware of such niceties as thousands separation and
2095dafa 940so on. (See L<The localeconv function> if you care about these things.)
5a964f20 941
b960a36e
KW
942 use POSIX qw(strtod setlocale LC_NUMERIC);
943 use locale;
5f05dabc 944
b960a36e 945 setlocale LC_NUMERIC, "";
14280422 946
b960a36e 947 $n = 5/2; # Assign numeric 2.5 to $n
5f05dabc 948
b960a36e 949 $a = " $n"; # Locale-dependent conversion to string
5f05dabc 950
b960a36e 951 print "half five is $n\n"; # Locale-dependent output
5f05dabc 952
b960a36e 953 printf "half five is %g\n", $n; # Locale-dependent output
5f05dabc 954
b960a36e
KW
955 print "DECIMAL POINT IS COMMA\n"
956 if $n == (strtod("2,5"))[0]; # Locale-dependent conversion
5f05dabc 957
4bbcc6e8
JH
958See also L<I18N::Langinfo> and C<RADIXCHAR>.
959
cb88b78e 960=head2 Category C<LC_MONETARY>: Formatting of monetary amounts
5f05dabc 961
e199995e 962The C standard defines the C<LC_MONETARY> category, but not a function
5a964f20 963that is affected by its contents. (Those with experience of standards
b0c42ed9 964committees will recognize that the working group decided to punt on the
fa9b773e
KW
965issue.) Consequently, Perl essentially takes no notice of it. If you
966really want to use C<LC_MONETARY>, you can query its contents--see
e05ffc7d
KW
967L<The localeconv function>--and use the information that it returns in your
968application's own formatting of currency amounts. However, you may well
969find that the information, voluminous and complex though it may be, still
970does not quite meet your requirements: currency formatting is a hard nut
13a2d996 971to crack.
5f05dabc 972
4bbcc6e8
JH
973See also L<I18N::Langinfo> and C<CRNCYSTR>.
974
cb88b78e 975=head2 C<LC_TIME>
5f05dabc 976
39332f68 977Output produced by C<POSIX::strftime()>, which builds a formatted
5f05dabc
PP
978human-readable date/time string, is affected by the current C<LC_TIME>
979locale. Thus, in a French locale, the output produced by the C<%B>
980format element (full month name) for the first month of the year would
5a964f20 981be "janvier". Here's how to get a list of long month names in the
5f05dabc
PP
982current locale:
983
984 use POSIX qw(strftime);
14280422
DD
985 for (0..11) {
986 $long_month_name[$_] =
987 strftime("%B", 0, 0, 0, 1, $_, 96);
5f05dabc
PP
988 }
989
2619d284
KW
990Note: C<use locale> isn't needed in this example: C<strftime()> is a POSIX
991function which uses the standard system-supplied C<libc> function that
992always obeys the current C<LC_TIME> locale.
5f05dabc 993
4bbcc6e8 994See also L<I18N::Langinfo> and C<ABDAY_1>..C<ABDAY_7>, C<DAY_1>..C<DAY_7>,
2a2bf5f4 995C<ABMON_1>..C<ABMON_12>, and C<ABMON_1>..C<ABMON_12>.
4bbcc6e8 996
5f05dabc
PP
997=head2 Other categories
998
2619d284
KW
999The remaining locale categories are not currently used by Perl itself.
1000But again note that things Perl interacts with may use these, including
1001extensions outside the standard Perl distribution, and by the
98a6f11e 1002operating system and its utilities. Note especially that the string
1003value of C<$!> and the error messages given by external utilities may
1004be changed by C<LC_MESSAGES>. If you want to have portable error
265f5c4a 1005codes, use C<%!>. See L<Errno>.
14280422
DD
1006
1007=head1 SECURITY
1008
5a964f20 1009Although the main discussion of Perl security issues can be found in
14280422
DD
1010L<perlsec>, a discussion of Perl's locale handling would be incomplete
1011if it did not draw your attention to locale-dependent security issues.
5a964f20
TC
1012Locales--particularly on systems that allow unprivileged users to
1013build their own locales--are untrustworthy. A malicious (or just plain
14280422
DD
1014broken) locale can make a locale-aware application give unexpected
1015results. Here are a few possibilities:
1016
1017=over 4
1018
1019=item *
1020
1021Regular expression checks for safe file names or mail addresses using
5a964f20 1022C<\w> may be spoofed by an C<LC_CTYPE> locale that claims that
dbf3c4d7 1023characters such as C<"E<gt>"> and C<"|"> are alphanumeric.
14280422
DD
1024
1025=item *
1026
e38874e2 1027String interpolation with case-mapping, as in, say, C<$dest =
cb88b78e 1028"C:\U$name.$ext">, may produce dangerous results if a bogus C<LC_CTYPE>
e38874e2
DD
1029case-mapping table is in effect.
1030
1031=item *
1032
14280422
DD
1033A sneaky C<LC_COLLATE> locale could result in the names of students with
1034"D" grades appearing ahead of those with "A"s.
1035
1036=item *
1037
5a964f20 1038An application that takes the trouble to use information in
14280422 1039C<LC_MONETARY> may format debits as if they were credits and vice versa
5a964f20 1040if that locale has been subverted. Or it might make payments in US
14280422
DD
1041dollars instead of Hong Kong dollars.
1042
1043=item *
1044
39332f68 1045The date and day names in dates formatted by C<strftime()> could be
14280422 1046manipulated to advantage by a malicious user able to subvert the
5a964f20 1047C<LC_DATE> locale. ("Look--it says I wasn't in the building on
14280422
DD
1048Sunday.")
1049
1050=back
1051
1052Such dangers are not peculiar to the locale system: any aspect of an
5a964f20 1053application's environment which may be modified maliciously presents
14280422 1054similar challenges. Similarly, they are not specific to Perl: any
5a964f20 1055programming language that allows you to write programs that take
14280422
DD
1056account of their environment exposes you to these issues.
1057
5a964f20
TC
1058Perl cannot protect you from all possibilities shown in the
1059examples--there is no substitute for your own vigilance--but, when
14280422 1060C<use locale> is in effect, Perl uses the tainting mechanism (see
5a964f20 1061L<perlsec>) to mark string results that become locale-dependent, and
14280422 1062which may be untrustworthy in consequence. Here is a summary of the
5a964f20 1063tainting behavior of operators and functions that may be affected by
14280422
DD
1064the locale:
1065
1066=over 4
1067
551e1d92
RB
1068=item *
1069
1070B<Comparison operators> (C<lt>, C<le>, C<ge>, C<gt> and C<cmp>):
14280422
DD
1071
1072Scalar true/false (or less/equal/greater) result is never tainted.
1073
551e1d92
RB
1074=item *
1075
1d2ab946 1076B<Case-mapping interpolation> (with C<\l>, C<\L>, C<\u>, C<\U>, or C<\F>)
e38874e2 1077
d6ded950
KW
1078The result string containing interpolated material is tainted if
1079a C<use locale> form that includes C<LC_CTYPE> is in effect.
e38874e2 1080
551e1d92
RB
1081=item *
1082
1083B<Matching operator> (C<m//>):
14280422
DD
1084
1085Scalar true/false result never tainted.
1086
1d2ab946 1087All subpatterns, either delivered as a list-context result or as C<$1>
d6ded950
KW
1088I<etc>., are tainted if a C<use locale> form that includes
1089C<LC_CTYPE> is in effect, and the subpattern
63baef57
KW
1090regular expression contains a locale-dependent construct. These
1091constructs include C<\w> (to match an alphanumeric character), C<\W>
1092(non-alphanumeric character), C<\b> and C<\B> (word-boundary and
1093non-boundardy, which depend on what C<\w> and C<\W> match), C<\s>
1094(whitespace character), C<\S> (non whitespace character), C<\d> and
1095C<\D> (digits and non-digits), and the POSIX character classes, such as
1096C<[:alpha:]> (see L<perlrecharclass/POSIX Character Classes>).
1097
1098Tainting is also likely if the pattern is to be matched
1099case-insensitively (via C</i>). The exception is if all the code points
1100to be matched this way are above 255 and do not have folds under Unicode
1101rules to below 256. Tainting is not done for these because Perl
1102only uses Unicode rules for such code points, and those rules are the
1103same no matter what the current locale.
1104
1d2ab946
KW
1105The matched-pattern variables, C<$&>, C<$`> (pre-match), C<$'>
1106(post-match), and C<$+> (last match) also are tainted.
14280422 1107
551e1d92
RB
1108=item *
1109
1110B<Substitution operator> (C<s///>):
14280422 1111
e38874e2 1112Has the same behavior as the match operator. Also, the left
d6ded950
KW
1113operand of C<=~> becomes tainted when a C<use locale>
1114form that includes C<LC_CTYPE> is in effect, if modified as
66cbab2c 1115a result of a substitution based on a regular
1d2ab946
KW
1116expression match involving any of the things mentioned in the previous
1117item, or of case-mapping, such as C<\l>, C<\L>,C<\u>, C<\U>, or C<\F>.
14280422 1118
551e1d92
RB
1119=item *
1120
39332f68 1121B<Output formatting functions> (C<printf()> and C<write()>):
14280422 1122
3cf03d68
JH
1123Results are never tainted because otherwise even output from print,
1124for example C<print(1/7)>, should be tainted if C<use locale> is in
1125effect.
14280422 1126
551e1d92
RB
1127=item *
1128
39332f68 1129B<Case-mapping functions> (C<lc()>, C<lcfirst()>, C<uc()>, C<ucfirst()>):
14280422 1130
d6ded950
KW
1131Results are tainted if a C<use locale> form that includes C<LC_CTYPE> is
1132in effect.
14280422 1133
551e1d92
RB
1134=item *
1135
39332f68
KW
1136B<POSIX locale-dependent functions> (C<localeconv()>, C<strcoll()>,
1137C<strftime()>, C<strxfrm()>):
14280422
DD
1138
1139Results are never tainted.
1140
14280422
DD
1141=back
1142
1143Three examples illustrate locale-dependent tainting.
1144The first program, which ignores its locale, won't run: a value taken
54310121 1145directly from the command line may not be used to name an output file
14280422
DD
1146when taint checks are enabled.
1147
1148 #/usr/local/bin/perl -T
1149 # Run with taint checking
1150
54310121 1151 # Command line sanity check omitted...
14280422
DD
1152 $tainted_output_file = shift;
1153
1154 open(F, ">$tainted_output_file")
3183d96c 1155 or warn "Open of $tainted_output_file failed: $!\n";
14280422
DD
1156
1157The program can be made to run by "laundering" the tainted value through
5a964f20
TC
1158a regular expression: the second example--which still ignores locale
1159information--runs, creating the file named on its command line
14280422
DD
1160if it can.
1161
1162 #/usr/local/bin/perl -T
1163
1164 $tainted_output_file = shift;
1165 $tainted_output_file =~ m%[\w/]+%;
1166 $untainted_output_file = $&;
1167
1168 open(F, ">$untainted_output_file")
1169 or warn "Open of $untainted_output_file failed: $!\n";
1170
5a964f20 1171Compare this with a similar but locale-aware program:
14280422
DD
1172
1173 #/usr/local/bin/perl -T
1174
1175 $tainted_output_file = shift;
1176 use locale;
1177 $tainted_output_file =~ m%[\w/]+%;
1178 $localized_output_file = $&;
1179
1180 open(F, ">$localized_output_file")
1181 or warn "Open of $localized_output_file failed: $!\n";
1182
1d2ab946 1183This third program fails to run because C<$&> is tainted: it is the result
5a964f20 1184of a match involving C<\w> while C<use locale> is in effect.
5f05dabc
PP
1185
1186=head1 ENVIRONMENT
1187
1188=over 12
1189
ee1ec05f
KW
1190=item PERL_SKIP_LOCALE_INIT
1191
c5c88224
KW
1192This environment variable, available starting in Perl v5.20, if set
1193(to any value), tells Perl to not use the rest of the
ee1ec05f
KW
1194environment variables to initialize with. Instead, Perl uses whatever
1195the current locale settings are. This is particularly useful in
1196embedded environments, see
1197L<perlembed/Using embedded Perl with POSIX locales>.
1198
5f05dabc
PP
1199=item PERL_BADLANG
1200
14280422 1201A string that can suppress Perl's warning about failed locale settings
54310121 1202at startup. Failure can occur if the locale support in the operating
5a964f20 1203system is lacking (broken) in some way--or if you mistyped the name of
900bd440 1204a locale when you set up your environment. If this environment
22ff3130
HS
1205variable is absent, or has a value other than "0" or "", Perl will
1206complain about locale setting failures.
5f05dabc 1207
cb88b78e 1208B<NOTE>: C<PERL_BADLANG> only gives you a way to hide the warning message.
14280422
DD
1209The message tells about some problem in your system's locale support,
1210and you should investigate what the problem is.
5f05dabc
PP
1211
1212=back
1213
1214The following environment variables are not specific to Perl: They are
39332f68 1215part of the standardized (ISO C, XPG4, POSIX 1.c) C<setlocale()> method
b385bb4d
KW
1216for controlling an application's opinion on data. Windows is non-POSIX,
1217but Perl arranges for the following to work as described anyway.
65ebb059
KW
1218If the locale given by an environment variable is not valid, Perl tries
1219the next lower one in priority. If none are valid, on Windows, the
1220system default locale is then tried. If all else fails, the C<"C">
1221locale is used. If even that doesn't work, something is badly broken,
c5e9a8e7 1222but Perl tries to forge ahead with whatever the locale settings might
65ebb059 1223be.
5f05dabc
PP
1224
1225=over 12
1226
cb88b78e 1227=item C<LC_ALL>
5f05dabc 1228
5a964f20 1229C<LC_ALL> is the "override-all" locale environment variable. If
5f05dabc
PP
1230set, it overrides all the rest of the locale environment variables.
1231
cb88b78e 1232=item C<LANGUAGE>
528d65ad
JH
1233
1234B<NOTE>: C<LANGUAGE> is a GNU extension, it affects you only if you
1235are using the GNU libc. This is the case if you are using e.g. Linux.
e1020413 1236If you are using "commercial" Unixes you are most probably I<not>
22b6f60d
JH
1237using GNU libc and you can ignore C<LANGUAGE>.
1238
1239However, in the case you are using C<LANGUAGE>: it affects the
1240language of informational, warning, and error messages output by
1241commands (in other words, it's like C<LC_MESSAGES>) but it has higher
96090e4f 1242priority than C<LC_ALL>. Moreover, it's not a single value but
22b6f60d
JH
1243instead a "path" (":"-separated list) of I<languages> (not locales).
1244See the GNU C<gettext> library documentation for more information.
528d65ad 1245
3ee1a09c 1246=item C<LC_CTYPE>
5f05dabc
PP
1247
1248In the absence of C<LC_ALL>, C<LC_CTYPE> chooses the character type
1249locale. In the absence of both C<LC_ALL> and C<LC_CTYPE>, C<LANG>
1250chooses the character type locale.
1251
cb88b78e 1252=item C<LC_COLLATE>
5f05dabc 1253
14280422
DD
1254In the absence of C<LC_ALL>, C<LC_COLLATE> chooses the collation
1255(sorting) locale. In the absence of both C<LC_ALL> and C<LC_COLLATE>,
1256C<LANG> chooses the collation locale.
5f05dabc 1257
cb88b78e 1258=item C<LC_MONETARY>
5f05dabc 1259
14280422
DD
1260In the absence of C<LC_ALL>, C<LC_MONETARY> chooses the monetary
1261formatting locale. In the absence of both C<LC_ALL> and C<LC_MONETARY>,
1262C<LANG> chooses the monetary formatting locale.
5f05dabc 1263
cb88b78e 1264=item C<LC_NUMERIC>
5f05dabc
PP
1265
1266In the absence of C<LC_ALL>, C<LC_NUMERIC> chooses the numeric format
1267locale. In the absence of both C<LC_ALL> and C<LC_NUMERIC>, C<LANG>
1268chooses the numeric format.
1269
cb88b78e 1270=item C<LC_TIME>
5f05dabc 1271
14280422
DD
1272In the absence of C<LC_ALL>, C<LC_TIME> chooses the date and time
1273formatting locale. In the absence of both C<LC_ALL> and C<LC_TIME>,
1274C<LANG> chooses the date and time formatting locale.
5f05dabc 1275
cb88b78e 1276=item C<LANG>
5f05dabc 1277
14280422
DD
1278C<LANG> is the "catch-all" locale environment variable. If it is set, it
1279is used as the last resort after the overall C<LC_ALL> and the
3ee1a09c 1280category-specific C<LC_I<foo>>.
5f05dabc
PP
1281
1282=back
1283
7e4353e9
RGS
1284=head2 Examples
1285
cb88b78e 1286The C<LC_NUMERIC> controls the numeric output:
7e4353e9 1287
ef3087ec
KW
1288 use locale;
1289 use POSIX qw(locale_h); # Imports setlocale() and the LC_ constants.
1290 setlocale(LC_NUMERIC, "fr_FR") or die "Pardon";
1291 printf "%g\n", 1.23; # If the "fr_FR" succeeded, probably shows 1,23.
7e4353e9 1292
39332f68 1293and also how strings are parsed by C<POSIX::strtod()> as numbers:
7e4353e9 1294
ef3087ec
KW
1295 use locale;
1296 use POSIX qw(locale_h strtod);
1297 setlocale(LC_NUMERIC, "de_DE") or die "Entschuldigung";
1298 my $x = strtod("2,34") + 5;
1299 print $x, "\n"; # Probably shows 7,34.
7e4353e9 1300
5f05dabc
PP
1301=head1 NOTES
1302
b960a36e
KW
1303=head2 String C<eval> and C<LC_NUMERIC>
1304
1305A string L<eval|perlfunc/eval EXPR> parses its expression as standard
1306Perl. It is therefore expecting the decimal point to be a dot. If
1307C<LC_NUMERIC> is set to have this be a comma instead, the parsing will
1308be confused, perhaps silently.
1309
1310 use locale;
1311 use POSIX qw(locale_h);
1312 setlocale(LC_NUMERIC, "fr_FR") or die "Pardon";
1313 my $a = 1.2;
1314 print eval "$a + 1.5";
1315 print "\n";
1316
1317prints C<13,5>. This is because in that locale, the comma is the
1318decimal point character. The C<eval> thus expands to:
1319
1320 eval "1,2 + 1.5"
1321
1322and the result is not what you likely expected. No warnings are
1323generated. If you do string C<eval>'s within the scope of
1324S<C<use locale>>, you should instead change the C<eval> line to do
1325something like:
1326
1327 print eval "no locale; $a + 1.5";
1328
1329This prints C<2.7>.
1330
d6ded950
KW
1331You could also exclude C<LC_NUMERIC>, if you don't need it, by
1332
1333 use locale ':!numeric';
1334
5f05dabc
PP
1335=head2 Backward compatibility
1336
b0c42ed9 1337Versions of Perl prior to 5.004 B<mostly> ignored locale information,
5a964f20
TC
1338generally behaving as if something similar to the C<"C"> locale were
1339always in force, even if the program environment suggested otherwise
1340(see L<The setlocale function>). By default, Perl still behaves this
1341way for backward compatibility. If you want a Perl application to pay
1342attention to locale information, you B<must> use the S<C<use locale>>
d6ded950 1343pragma (see L<The "use locale" pragma>) or, in the unlikely event
062ca197 1344that you want to do so for just pattern matching, the
70709c68
KW
1345C</l> regular expression modifier (see L<perlre/Character set
1346modifiers>) to instruct it to do so.
b0c42ed9
JH
1347
1348Versions of Perl from 5.002 to 5.003 did use the C<LC_CTYPE>
5a964f20
TC
1349information if available; that is, C<\w> did understand what
1350were the letters according to the locale environment variables.
b0c42ed9
JH
1351The problem was that the user had no control over the feature:
1352if the C library supported locales, Perl used them.
1353
1354=head2 I18N:Collate obsolete
1355
5a964f20 1356In versions of Perl prior to 5.004, per-locale collation was possible
b0c42ed9
JH
1357using the C<I18N::Collate> library module. This module is now mildly
1358obsolete and should be avoided in new applications. The C<LC_COLLATE>
1359functionality is now integrated into the Perl core language: One can
1360use locale-specific scalar data completely normally with C<use locale>,
1361so there is no longer any need to juggle with the scalar references of
1362C<I18N::Collate>.
5f05dabc 1363
14280422 1364=head2 Sort speed and memory use impacts
5f05dabc
PP
1365
1366Comparing and sorting by locale is usually slower than the default
14280422
DD
1367sorting; slow-downs of two to four times have been observed. It will
1368also consume more memory: once a Perl scalar variable has participated
1369in any string comparison or sorting operation obeying the locale
1370collation rules, it will take 3-15 times more memory than before. (The
1371exact multiplier depends on the string's contents, the operating system
1372and the locale.) These downsides are dictated more by the operating
1373system's implementation of the locale system than by Perl.
5f05dabc 1374
5f05dabc
PP
1375=head2 Freely available locale definitions
1376
66cbab2c
KW
1377The Unicode CLDR project extracts the POSIX portion of many of its
1378locales, available at
1379
e784ce68
KW
1380 http://unicode.org/Public/cldr/2.0.1/
1381
1382(Newer versions of CLDR require you to compute the POSIX data yourself.
1383See L<http://unicode.org/Public/cldr/latest/>.)
66cbab2c 1384
08d7a6b2
LB
1385There is a large collection of locale definitions at:
1386
1387 http://std.dkuug.dk/i18n/WG15-collection/locales/
1388
1389You should be aware that it is
14280422 1390unsupported, and is not claimed to be fit for any purpose. If your
5a964f20 1391system allows installation of arbitrary locales, you may find the
14280422
DD
1392definitions useful as they are, or as a basis for the development of
1393your own locales.
5f05dabc 1394
14280422 1395=head2 I18n and l10n
5f05dabc 1396
b0c42ed9
JH
1397"Internationalization" is often abbreviated as B<i18n> because its first
1398and last letters are separated by eighteen others. (You may guess why
1399the internalin ... internaliti ... i18n tends to get abbreviated.) In
1400the same way, "localization" is often abbreviated to B<l10n>.
14280422
DD
1401
1402=head2 An imperfect standard
1403
1404Internationalization, as defined in the C and POSIX standards, can be
1405criticized as incomplete, ungainly, and having too large a granularity.
1406(Locales apply to a whole process, when it would arguably be more useful
1407to have them apply to a single thread, window group, or whatever.) They
1408also have a tendency, like standards groups, to divide the world into
1409nations, when we all know that the world can equally well be divided
e199995e 1410into bankers, bikers, gamers, and so on.
5f05dabc 1411
b310b053
JH
1412=head1 Unicode and UTF-8
1413
7ee2ae1e 1414The support of Unicode is new starting from Perl version v5.6, and more fully
31f05a37
KW
1415implemented in versions v5.8 and later. See L<perluniintro>.
1416
1417Starting in Perl v5.20, UTF-8 locales are supported in Perl, except for
1418C<LC_COLLATE> (use L<Unicode::Collate> instead). If you have Perl v5.16
1419or v5.18 and can't upgrade, you can use
66cbab2c
KW
1420
1421 use locale ':not_characters';
1422
1423When this form of the pragma is used, only the non-character portions of
1424locales are used by Perl, for example C<LC_NUMERIC>. Perl assumes that
1425you have translated all the characters it is to operate on into Unicode
1426(actually the platform's native character set (ASCII or EBCDIC) plus
1427Unicode). For data in files, this can conveniently be done by also
1428specifying
1429
1430 use open ':locale';
1431
1432This pragma arranges for all inputs from files to be translated into
1433Unicode from the current locale as specified in the environment (see
1434L</ENVIRONMENT>), and all outputs to files to be translated back
1435into the locale. (See L<open>). On a per-filehandle basis, you can
1436instead use the L<PerlIO::locale> module, or the L<Encode::Locale>
1437module, both available from CPAN. The latter module also has methods to
1438ease the handling of C<ARGV> and environment variables, and can be used
31f05a37 1439on individual strings. If you know that all your locales will be
66cbab2c
KW
1440UTF-8, as many are these days, you can use the L<B<-C>|perlrun/-C>
1441command line switch.
1442
1443This form of the pragma allows essentially seamless handling of locales
31f05a37
KW
1444with Unicode. The collation order will be by Unicode code point order.
1445It is strongly
66cbab2c
KW
1446recommended that when you need to order and sort strings that you use
1447the standard module L<Unicode::Collate> which gives much better results
1448in many instances than you can get with the old-style locale handling.
1449
31f05a37
KW
1450All the modules and switches just described can be used in v5.20 with
1451just plain C<use locale>, and, should the input locales not be UTF-8,
1452you'll get the less than ideal behavior, described below, that you get
1453with pre-v5.16 Perls, or when you use the locale pragma without the
1454C<:not_characters> parameter in v5.16 and v5.18. If you are using
1455exclusively UTF-8 locales in v5.20 and higher, the rest of this section
1456does not apply to you.
1457
1458There are two cases, multi-byte and single-byte locales. First
1459multi-byte:
1460
1461The only multi-byte (or wide character) locale that Perl is ever likely
1462to support is UTF-8. This is due to the difficulty of implementation,
1463the fact that high quality UTF-8 locales are now published for every
e784ce68
KW
1464area of the world (L<http://unicode.org/Public/cldr/2.0.1/> for
1465ones that are already set-up, but from an earlier version;
1466L<http://unicode.org/Public/cldr/latest/> for the most up-to-date, but
1467you have to extract the POSIX information yourself), and that
31f05a37
KW
1468failing all that you can use the L<Encode> module to translate to/from
1469your locale. So, you'll have to do one of those things if you're using
1470one of these locales, such as Big5 or Shift JIS. For UTF-8 locales, in
1471Perls (pre v5.20) that don't have full UTF-8 locale support, they may
1472work reasonably well (depending on your C library implementation)
1473simply because both
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1474they and Perl store characters that take up multiple bytes the same way.
1475However, some, if not most, C library implementations may not process
1476the characters in the upper half of the Latin-1 range (128 - 255)
cb88b78e 1477properly under C<LC_CTYPE>. To see if a character is a particular type
dc4bfc4b
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1478under a locale, Perl uses the functions like C<isalnum()>. Your C
1479library may not work for UTF-8 locales with those functions, instead
dbf3c4d7
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1480only working under the newer wide library functions like C<iswalnum()>,
1481which Perl does not use.
1482These multi-byte locales are treated like single-byte locales, and will
1483have the restrictions described below. Starting in Perl v5.22 a warning
1484message is raised when Perl detects a multi-byte locale that it doesn't
1485fully support.
e199995e 1486
31f05a37 1487For single-byte locales,
e199995e 1488Perl generally takes the tack to use locale rules on code points that can fit
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1489in a single byte, and Unicode rules for those that can't (though this
1490isn't uniformly applied, see the note at the end of this section). This
1491prevents many problems in locales that aren't UTF-8. Suppose the locale
1492is ISO8859-7, Greek. The character at 0xD7 there is a capital Chi. But
1493in the ISO8859-1 locale, Latin1, it is a multiplication sign. The POSIX
1494regular expression character class C<[[:alpha:]]> will magically match
14950xD7 in the Greek locale but not in the Latin one.
e199995e 1496
1d2ab946 1497However, there are places where this breaks down. Certain Perl constructs are
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TC
1498for Unicode only, such as C<\p{Alpha}>. They assume that 0xD7 always has its
1499Unicode meaning (or the equivalent on EBCDIC platforms). Since Latin1 is a
1500subset of Unicode and 0xD7 is the multiplication sign in both Latin1 and
1501Unicode, C<\p{Alpha}> will never match it, regardless of locale. A similar
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1502issue occurs with C<\N{...}>. Prior to v5.20, It is therefore a bad
1503idea to use C<\p{}> or
66cbab2c 1504C<\N{}> under plain C<use locale>--I<unless> you can guarantee that the
dbf3c4d7 1505locale will be ISO8859-1. Use POSIX character classes instead.
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1506
1507Another problem with this approach is that operations that cross the
1508single byte/multiple byte boundary are not well-defined, and so are
4a70680a 1509disallowed. (This boundary is between the codepoints at 255/256.)
66cbab2c
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1510For example, lower casing LATIN CAPITAL LETTER Y WITH DIAERESIS (U+0178)
1511should return LATIN SMALL LETTER Y WITH DIAERESIS (U+00FF). But in the
1512Greek locale, for example, there is no character at 0xFF, and Perl
1513has no way of knowing what the character at 0xFF is really supposed to
1514represent. Thus it disallows the operation. In this mode, the
1515lowercase of U+0178 is itself.
1516
1517The same problems ensue if you enable automatic UTF-8-ification of your
e199995e 1518standard file handles, default C<open()> layer, and C<@ARGV> on non-ISO8859-1,
b4ffc3db
TC
1519non-UTF-8 locales (by using either the B<-C> command line switch or the
1520C<PERL_UNICODE> environment variable; see L<perlrun>).
1521Things are read in as UTF-8, which would normally imply a Unicode
1522interpretation, but the presence of a locale causes them to be interpreted
1523in that locale instead. For example, a 0xD7 code point in the Unicode
1524input, which should mean the multiplication sign, won't be interpreted by
66cbab2c 1525Perl that way under the Greek locale. This is not a problem
b4ffc3db 1526I<provided> you make certain that all locales will always and only be either
66cbab2c 1527an ISO8859-1, or, if you don't have a deficient C library, a UTF-8 locale.
b4ffc3db 1528
1d2ab946
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1529Still another problem is that this approach can lead to two code
1530points meaning the same character. Thus in a Greek locale, both U+03A7
1531and U+00D7 are GREEK CAPITAL LETTER CHI.
1532
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1533Because of all these problems, starting in v5.22, Perl will raise a
1534warning if a multi-byte (hence Unicode) code point is used when a
1535single-byte locale is in effect. (Although it doesn't check for this if
1536doing so would unreasonably slow execution down.)
1537
b4ffc3db
TC
1538Vendor locales are notoriously buggy, and it is difficult for Perl to test
1539its locale-handling code because this interacts with code that Perl has no
1540control over; therefore the locale-handling code in Perl may be buggy as
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KW
1541well. (However, the Unicode-supplied locales should be better, and
1542there is a feed back mechanism to correct any problems. See
1543L</Freely available locale definitions>.)
1544
7ee2ae1e 1545If you have Perl v5.16, the problems mentioned above go away if you use
66cbab2c 1546the C<:not_characters> parameter to the locale pragma (except for vendor
7ee2ae1e 1547bugs in the non-character portions). If you don't have v5.16, and you
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1548I<do> have locales that work, using them may be worthwhile for certain
1549specific purposes, as long as you keep in mind the gotchas already
1550mentioned. For example, if the collation for your locales works, it
1551runs faster under locales than under L<Unicode::Collate>; and you gain
1552access to such things as the local currency symbol and the names of the
7ee2ae1e 1553months and days of the week. (But to hammer home the point, in v5.16,
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1554you get this access without the downsides of locales by using the
1555C<:not_characters> form of the pragma.)
1556
1557Note: The policy of using locale rules for code points that can fit in a
1558byte, and Unicode rules for those that can't is not uniformly applied.
7ee2ae1e 1559Pre-v5.12, it was somewhat haphazard; in v5.12 it was applied fairly
66cbab2c 1560consistently to regular expression matching except for bracketed
7ee2ae1e 1561character classes; in v5.14 it was extended to all regex matches; and in
663d437a 1562v5.16 to the casing operations such as C<\L> and C<uc()>. For
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1563collation, in all releases so far, the system's C<strxfrm()> function is
1564called, and whatever it does is what you get.
b310b053 1565
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1566=head1 BUGS
1567
1568=head2 Broken systems
1569
5a964f20 1570In certain systems, the operating system's locale support
2bdf8add 1571is broken and cannot be fixed or used by Perl. Such deficiencies can
b4ffc3db 1572and will result in mysterious hangs and/or Perl core dumps when
2bdf8add 1573C<use locale> is in effect. When confronted with such a system,
7f2de2d2 1574please report in excruciating detail to <F<perlbug@perl.org>>, and
b4ffc3db 1575also contact your vendor: bug fixes may exist for these problems
2bdf8add 1576in your operating system. Sometimes such bug fixes are called an
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1577operating system upgrade. If you have the source for Perl, include in
1578the perlbug email the output of the test described above in L</Testing
1579for broken locales>.
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1580
1581=head1 SEE ALSO
1582
b310b053
JH
1583L<I18N::Langinfo>, L<perluniintro>, L<perlunicode>, L<open>,
1584L<POSIX/isalnum>, L<POSIX/isalpha>,
4bbcc6e8
JH
1585L<POSIX/isdigit>, L<POSIX/isgraph>, L<POSIX/islower>,
1586L<POSIX/isprint>, L<POSIX/ispunct>, L<POSIX/isspace>,
1587L<POSIX/isupper>, L<POSIX/isxdigit>, L<POSIX/localeconv>,
1588L<POSIX/setlocale>, L<POSIX/strcoll>, L<POSIX/strftime>,
1589L<POSIX/strtod>, L<POSIX/strxfrm>.
5f05dabc 1590
ccd65d51
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1591For special considerations when Perl is embedded in a C program,
1592see L<perlembed/Using embedded Perl with POSIX locales>.
1593
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PP
1594=head1 HISTORY
1595
b0c42ed9 1596Jarkko Hietaniemi's original F<perli18n.pod> heavily hacked by Dominic
5a964f20 1597Dunlop, assisted by the perl5-porters. Prose worked over a bit by
c052850d 1598Tom Christiansen, and updated by Perl 5 porters.