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perllocale: Correctly document behavior
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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
5c25e937 35UTF-8 locales, except for sorting and string comparisons. (Use
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36L<Unicode::Collate> for these.) Perl continues to support the old
37non UTF-8 locales as well.
38
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39(Unicode is also creating C<CLDR>, the "Common Locale Data Repository",
40L<http://cldr.unicode.org/> which includes more types of information than
41are available in the POSIX locale system. At the time of this writing,
42there was no CPAN module that provides access to this XML-encoded data.
43However, many of its locales have the POSIX-only data extracted, and are
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44available as UTF-8 locales at
45L<http://unicode.org/Public/cldr/latest/>.)
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46
47=head1 WHAT IS A LOCALE
48
49A locale is a set of data that describes various aspects of how various
50communities in the world categorize their world. These categories are
51broken down into the following types (some of which include a brief
52note here):
53
54=over
55
cb88b78e 56=item Category C<LC_NUMERIC>: Numeric formatting
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57
58This indicates how numbers should be formatted for human readability,
59for example the character used as the decimal point.
60
cb88b78e 61=item Category C<LC_MONETARY>: Formatting of monetary amounts
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62
63=for comment
ebc3223b 64The nbsp below makes this look better (though not great)
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65
66E<160>
67
cb88b78e 68=item Category C<LC_TIME>: Date/Time formatting
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69
70=for comment
ebc3223b 71The nbsp below makes this look better (though not great)
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72
73E<160>
74
cb88b78e 75=item Category C<LC_MESSAGES>: Error and other messages
66cbab2c 76
2619d284 77This is used by Perl itself only for accessing operating system error
03c702c5 78messages via L<$!|perlvar/$ERRNO> and L<$^E|perlvar/$EXTENDED_OS_ERROR>.
66cbab2c 79
cb88b78e 80=item Category C<LC_COLLATE>: Collation
66cbab2c 81
76073c88 82This indicates the ordering of letters for comparison and sorting.
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83In Latin alphabets, for example, "b", generally follows "a".
84
cb88b78e 85=item Category C<LC_CTYPE>: Character Types
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86
87This indicates, for example if a character is an uppercase letter.
88
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89=item Other categories
90
91Some platforms have other categories, dealing with such things as
92measurement units and paper sizes. None of these are used directly by
93Perl, but outside operations that Perl interacts with may use
d6ded950 94these. See L</Not within the scope of "use locale"> below.
2619d284 95
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96=back
97
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98More details on the categories used by Perl are given below in L</LOCALE
99CATEGORIES>.
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100
101Together, these categories go a long way towards being able to customize
102a single program to run in many different locations. But there are
103deficiencies, so keep reading.
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104
105=head1 PREPARING TO USE LOCALES
106
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107Perl itself (outside the L<POSIX> module) will not use locales unless
108specifically requested to (but
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109again note that Perl may interact with code that does use them). Even
110if there is such a request, B<all> of the following must be true
b960a36e 111for it to work properly:
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112
113=over 4
114
115=item *
116
117B<Your operating system must support the locale system>. If it does,
39332f68 118you should find that the C<setlocale()> function is a documented part of
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119its C library.
120
121=item *
122
5a964f20 123B<Definitions for locales that you use must be installed>. You, or
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124your system administrator, must make sure that this is the case. The
125available locales, the location in which they are kept, and the manner
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126in which they are installed all vary from system to system. Some systems
127provide only a few, hard-wired locales and do not allow more to be
128added. Others allow you to add "canned" locales provided by the system
129supplier. Still others allow you or the system administrator to define
14280422 130and add arbitrary locales. (You may have to ask your supplier to
5a964f20 131provide canned locales that are not delivered with your operating
14280422 132system.) Read your system documentation for further illumination.
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133
134=item *
135
136B<Perl must believe that the locale system is supported>. If it does,
137C<perl -V:d_setlocale> will say that the value for C<d_setlocale> is
138C<define>.
139
140=back
141
142If you want a Perl application to process and present your data
143according to a particular locale, the application code should include
d6ded950 144the S<C<use locale>> pragma (see L<The "use locale" pragma>) where
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145appropriate, and B<at least one> of the following must be true:
146
147=over 4
148
c052850d 149=item 1
5f05dabc 150
66cbab2c 151B<The locale-determining environment variables (see L</"ENVIRONMENT">)
5a964f20 152must be correctly set up> at the time the application is started, either
ef3087ec 153by yourself or by whomever set up your system account; or
5f05dabc 154
c052850d 155=item 2
5f05dabc 156
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157B<The application must set its own locale> using the method described in
158L<The setlocale function>.
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159
160=back
161
162=head1 USING LOCALES
163
d6ded950 164=head2 The C<"use locale"> pragma
5f05dabc 165
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166By default, Perl itself (outside the L<POSIX> module)
167ignores the current locale. The S<C<use locale>>
66cbab2c 168pragma tells Perl to use the current locale for some operations.
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169Starting in v5.16, there are optional parameters to this pragma,
170described below, which restrict which operations are affected by it.
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171
172The current locale is set at execution time by
173L<setlocale()|/The setlocale function> described below. If that function
174hasn't yet been called in the course of the program's execution, the
66cbab2c 175current locale is that which was determined by the L</"ENVIRONMENT"> in
ebc3223b 176effect at the start of the program.
dfcc8045 177If there is no valid environment, the current locale is whatever the
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178system default has been set to. On POSIX systems, it is likely, but
179not necessarily, the "C" locale. On Windows, the default is set via the
180computer's S<C<Control Panel-E<gt>Regional and Language Options>> (or its
181current equivalent).
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182
183The operations that are affected by locale are:
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184
185=over 4
186
d6ded950 187=item B<Not within the scope of C<"use locale">>
b960a36e 188
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189Only certain operations originating outside Perl should be affected, as
190follows:
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191
192=over 4
193
194=item *
2619d284 195
663d437a 196The current locale is used when going outside of Perl with
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197operations like L<system()|perlfunc/system LIST> or
198L<qxE<sol>E<sol>|perlop/qxE<sol>STRINGE<sol>>, if those operations are
199locale-sensitive.
200
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201=item *
202
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203Also Perl gives access to various C library functions through the
204L<POSIX> module. Some of those functions are always affected by the
205current locale. For example, C<POSIX::strftime()> uses C<LC_TIME>;
206C<POSIX::strtod()> uses C<LC_NUMERIC>; C<POSIX::strcoll()> and
207C<POSIX::strxfrm()> use C<LC_COLLATE>; and character classification
208functions like C<POSIX::isalnum()> use C<LC_CTYPE>. All such functions
209will behave according to the current underlying locale, even if that
1d2ab946 210locale isn't exposed to Perl space.
2619d284 211
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212=item *
213
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214XS modules for all categories but C<LC_NUMERIC> get the underlying
215locale, and hence any C library functions they call will use that
8a384d3a 216underlying locale. For more discussion, see L<perlxs/CAVEATS>.
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217
218=back
219
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220Note that all C programs (including the perl interpreter, which is
221written in C) always have an underlying locale. That locale is the "C"
222locale unless changed by a call to L<setlocale()|/The setlocale
223function>. When Perl starts up, it changes the underlying locale to the
224one which is indicated by the L</ENVIRONMENT>. When using the L<POSIX>
225module or writing XS code, it is important to keep in mind that the
226underlying locale may be something other than "C", even if the program
227hasn't explicitly changed it.
228
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229=for comment
230The nbsp below makes this look better (though not great)
231
232E<160>
233
234=item B<Lingering effects of C<S<use locale>>>
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235
236Certain Perl operations that are set-up within the scope of a
d6ded950 237C<use locale> retain that effect even outside the scope.
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238These include:
239
240=over 4
241
242=item *
243
244The output format of a L<write()|perlfunc/write> is determined by an
245earlier format declaration (L<perlfunc/format>), so whether or not the
246output is affected by locale is determined by if the C<format()> is
d6ded950 247within the scope of a C<use locale>, not whether the C<write()>
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248is.
249
250=item *
251
252Regular expression patterns can be compiled using
33be4c61 253L<qrE<sol>E<sol>|perlop/qrE<sol>STRINGE<sol>msixpodualn> with actual
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254matching deferred to later. Again, it is whether or not the compilation
255was done within the scope of C<use locale> that determines the match
256behavior, not if the matches are done within such a scope or not.
257
258=back
259
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260=for comment
261The nbsp below makes this look better (though not great)
262
d6ded950 263
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264E<160>
265
d6ded950 266=item B<Under C<"use locale";>>
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267
268=over 4
269
270=item *
271
d6ded950 272All the above operations
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273
274=item *
275
276B<Format declarations> (L<perlfunc/format>) and hence any subsequent
277C<write()>s use C<LC_NUMERIC>.
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278
279=item *
280
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281B<stringification and output> use C<LC_NUMERIC>.
282These include the results of
283C<print()>,
284C<printf()>,
285C<say()>,
286and
287C<sprintf()>.
66cbab2c 288
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289=item *
290
291B<The comparison operators> (C<lt>, C<le>, C<cmp>, C<ge>, and C<gt>) use
39332f68 292C<LC_COLLATE>. C<sort()> is also affected if used without an
5a964f20 293explicit comparison function, because it uses C<cmp> by default.
14280422 294
5a964f20 295B<Note:> C<eq> and C<ne> are unaffected by locale: they always
de108802 296perform a char-by-char comparison of their scalar operands. What's
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297more, if C<cmp> finds that its operands are equal according to the
298collation sequence specified by the current locale, it goes on to
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299perform a char-by-char comparison, and only returns I<0> (equal) if the
300operands are char-for-char identical. If you really want to know whether
5a964f20 301two strings--which C<eq> and C<cmp> may consider different--are equal
14280422 302as far as collation in the locale is concerned, see the discussion in
cb88b78e 303L<Category C<LC_COLLATE>: Collation>.
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304
305=item *
306
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307B<Regular expressions and case-modification functions> (C<uc()>, C<lc()>,
308C<ucfirst()>, and C<lcfirst()>) use C<LC_CTYPE>
5f05dabc 309
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310=item *
311
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312B<The variables L<$!|perlvar/$ERRNO>> (and its synonyms C<$ERRNO> and
313C<$OS_ERROR>) B<and L<$^E|perlvar/$EXTENDED_OS_ERROR>> (and its synonym
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314C<$EXTENDED_OS_ERROR>) when used as strings use C<LC_MESSAGES>.
315
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316=back
317
66cbab2c 318=back
5f05dabc 319
5a964f20 320The default behavior is restored with the S<C<no locale>> pragma, or
ef3087ec 321upon reaching the end of the block enclosing C<use locale>.
3cd61afa 322Note that C<use locale> calls may be
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323nested, and that what is in effect within an inner scope will revert to
324the outer scope's rules at the end of the inner scope.
5f05dabc 325
5a964f20 326The string result of any operation that uses locale
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327information is tainted, as it is possible for a locale to be
328untrustworthy. See L<"SECURITY">.
5f05dabc 329
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330Starting in Perl v5.16 in a very limited way, and more generally in
331v5.22, you can restrict which category or categories are enabled by this
332particular instance of the pragma by adding parameters to it. For
333example,
334
335 use locale qw(:ctype :numeric);
336
337enables locale awareness within its scope of only those operations
338(listed above) that are affected by C<LC_CTYPE> and C<LC_NUMERIC>.
339
340The possible categories are: C<:collate>, C<:ctype>, C<:messages>,
341C<:monetary>, C<:numeric>, C<:time>, and the pseudo category
342C<:characters> (described below).
343
344Thus you can say
345
346 use locale ':messages';
347
348and only L<$!|perlvar/$ERRNO> and L<$^E|perlvar/$EXTENDED_OS_ERROR>
349will be locale aware. Everything else is unaffected.
350
351Since Perl doesn't currently do anything with the C<LC_MONETARY>
352category, specifying C<:monetary> does effectively nothing. Some
353systems have other categories, such as C<LC_PAPER_SIZE>, but Perl
354also doesn't know anything about them, and there is no way to specify
355them in this pragma's arguments.
356
357You can also easily say to use all categories but one, by either, for
358example,
359
360 use locale ':!ctype';
361 use locale ':not_ctype';
362
363both of which mean to enable locale awarness of all categories but
364C<LC_CTYPE>. Only one category argument may be specified in a
365S<C<use locale>> if it is of the negated form.
366
367Prior to v5.22 only one form of the pragma with arguments is available:
368
369 use locale ':not_characters';
370
371(and you have to say C<not_>; you can't use the bang C<!> form). This
372pseudo category is a shorthand for specifying both C<:collate> and
373C<:ctype>. Hence, in the negated form, it is nearly the same thing as
374saying
375
376 use locale qw(:messages :monetary :numeric :time);
377
378We use the term "nearly", because C<:not_characters> also turns on
379S<C<use feature 'unicode_strings'>> within its scope. This form is
380less useful in v5.20 and later, and is described fully in
381L</Unicode and UTF-8>, but briefly, it tells Perl to not use the
382character portions of the locale definition, that is the C<LC_CTYPE> and
383C<LC_COLLATE> categories. Instead it will use the native character set
384(extended by Unicode). When using this parameter, you are responsible
385for getting the external character set translated into the
386native/Unicode one (which it already will be if it is one of the
387increasingly popular UTF-8 locales). There are convenient ways of doing
388this, as described in L</Unicode and UTF-8>.
389
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390=head2 The setlocale function
391
14280422 392You can switch locales as often as you wish at run time with the
39332f68 393C<POSIX::setlocale()> function:
5f05dabc 394
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395 # Import locale-handling tool set from POSIX module.
396 # This example uses: setlocale -- the function call
397 # LC_CTYPE -- explained below
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398 # (Showing the testing for success/failure of operations is
399 # omitted in these examples to avoid distracting from the main
ebc3223b 400 # point)
6ea81ccf 401
5f05dabc 402 use POSIX qw(locale_h);
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403 use locale;
404 my $old_locale;
5f05dabc 405
14280422 406 # query and save the old locale
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407 $old_locale = setlocale(LC_CTYPE);
408
409 setlocale(LC_CTYPE, "fr_CA.ISO8859-1");
410 # LC_CTYPE now in locale "French, Canada, codeset ISO 8859-1"
411
412 setlocale(LC_CTYPE, "");
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413 # LC_CTYPE now reset to the default defined by the
414 # LC_ALL/LC_CTYPE/LANG environment variables, or to the system
415 # default. See below for documentation.
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416
417 # restore the old locale
418 setlocale(LC_CTYPE, $old_locale);
419
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420This simultaneously affects all threads of the program, so it may be
421problematic to use locales in threaded applications except where there
422is a single locale applicable to all threads.
423
39332f68 424The first argument of C<setlocale()> gives the B<category>, the second the
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425B<locale>. The category tells in what aspect of data processing you
426want to apply locale-specific rules. Category names are discussed in
66cbab2c 427L</LOCALE CATEGORIES> and L</"ENVIRONMENT">. The locale is the name of a
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428collection of customization information corresponding to a particular
429combination of language, country or territory, and codeset. Read on for
430hints on the naming of locales: not all systems name locales as in the
431example.
432
39332f68 433If no second argument is provided and the category is something other
cb88b78e 434than C<LC_ALL>, the function returns a string naming the current locale
502a173a 435for the category. You can use this value as the second argument in a
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436subsequent call to C<setlocale()>, B<but> on some platforms the string
437is opaque, not something that most people would be able to decipher as
438to what locale it means.
502a173a 439
cb88b78e 440If no second argument is provided and the category is C<LC_ALL>, the
502a173a 441result is implementation-dependent. It may be a string of
c052850d 442concatenated locale names (separator also implementation-dependent)
39332f68 443or a single locale name. Please consult your L<setlocale(3)> man page for
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444details.
445
446If a second argument is given and it corresponds to a valid locale,
447the locale for the category is set to that value, and the function
448returns the now-current locale value. You can then use this in yet
39332f68 449another call to C<setlocale()>. (In some implementations, the return
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450value may sometimes differ from the value you gave as the second
451argument--think of it as an alias for the value you gave.)
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452
453As the example shows, if the second argument is an empty string, the
454category's locale is returned to the default specified by the
455corresponding environment variables. Generally, this results in a
5a964f20 456return to the default that was in force when Perl started up: changes
54310121 457to the environment made by the application after startup may or may not
5a964f20 458be noticed, depending on your system's C library.
5f05dabc 459
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460Note that when a form of C<use locale> that doesn't include all
461categories is specified, Perl ignores the excluded categories.
66cbab2c 462
f170b852 463If C<set_locale()> fails for some reason (for example, an attempt to set
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464to a locale unknown to the system), the locale for the category is not
465changed, and the function returns C<undef>.
466
2619d284 467
39332f68 468For further information about the categories, consult L<setlocale(3)>.
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469
470=head2 Finding locales
471
39332f68 472For locales available in your system, consult also L<setlocale(3)> to
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473see whether it leads to the list of available locales (search for the
474I<SEE ALSO> section). If that fails, try the following command lines:
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475
476 locale -a
477
478 nlsinfo
479
480 ls /usr/lib/nls/loc
481
482 ls /usr/lib/locale
483
484 ls /usr/lib/nls
485
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486 ls /usr/share/locale
487
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488and see whether they list something resembling these
489
2bdf8add 490 en_US.ISO8859-1 de_DE.ISO8859-1 ru_RU.ISO8859-5
502a173a 491 en_US.iso88591 de_DE.iso88591 ru_RU.iso88595
2bdf8add 492 en_US de_DE ru_RU
14280422 493 en de ru
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494 english german russian
495 english.iso88591 german.iso88591 russian.iso88595
502a173a 496 english.roman8 russian.koi8r
5f05dabc 497
39332f68 498Sadly, even though the calling interface for C<setlocale()> has been
528d65ad 499standardized, names of locales and the directories where the
5a964f20 500configuration resides have not been. The basic form of the name is
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501I<language_territory>B<.>I<codeset>, but the latter parts after
502I<language> are not always present. The I<language> and I<country>
503are usually from the standards B<ISO 3166> and B<ISO 639>, the
504two-letter abbreviations for the countries and the languages of the
505world, respectively. The I<codeset> part often mentions some B<ISO
5068859> character set, the Latin codesets. For example, C<ISO 8859-1>
507is the so-called "Western European codeset" that can be used to encode
508most Western European languages adequately. Again, there are several
509ways to write even the name of that one standard. Lamentably.
5f05dabc 510
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511Two special locales are worth particular mention: "C" and "POSIX".
512Currently these are effectively the same locale: the difference is
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513mainly that the first one is defined by the C standard, the second by
514the POSIX standard. They define the B<default locale> in which
14280422 515every program starts in the absence of locale information in its
5a964f20 516environment. (The I<default> default locale, if you will.) Its language
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517is (American) English and its character codeset ASCII or, rarely, a
518superset thereof (such as the "DEC Multinational Character Set
519(DEC-MCS)"). B<Warning>. The C locale delivered by some vendors
520may not actually exactly match what the C standard calls for. So
521beware.
5f05dabc 522
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523B<NOTE>: Not all systems have the "POSIX" locale (not all systems are
524POSIX-conformant), so use "C" when you need explicitly to specify this
525default locale.
5f05dabc 526
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527=head2 LOCALE PROBLEMS
528
5a964f20 529You may encounter the following warning message at Perl startup:
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530
531 perl: warning: Setting locale failed.
532 perl: warning: Please check that your locale settings:
533 LC_ALL = "En_US",
534 LANG = (unset)
535 are supported and installed on your system.
536 perl: warning: Falling back to the standard locale ("C").
537
cb88b78e 538This means that your locale settings had C<LC_ALL> set to "En_US" and
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539LANG exists but has no value. Perl tried to believe you but could not.
540Instead, Perl gave up and fell back to the "C" locale, the default locale
65ebb059
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541that is supposed to work no matter what. (On Windows, it first tries
542falling back to the system default locale.) This usually means your
543locale settings were wrong, they mention locales your system has never
544heard of, or the locale installation in your system has problems (for
545example, some system files are broken or missing). There are quick and
546temporary fixes to these problems, as well as more thorough and lasting
547fixes.
3e6e419a 548
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549=head2 Testing for broken locales
550
551If you are building Perl from source, the Perl test suite file
552F<lib/locale.t> can be used to test the locales on your system.
553Setting the environment variable C<PERL_DEBUG_FULL_TEST> to 1
554will cause it to output detailed results. For example, on Linux, you
555could say
556
1d2ab946 557 PERL_DEBUG_FULL_TEST=1 ./perl -T -Ilib lib/locale.t > locale.log 2>&1
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558
559Besides many other tests, it will test every locale it finds on your
560system to see if they conform to the POSIX standard. If any have
561errors, it will include a summary near the end of the output of which
562locales passed all its tests, and which failed, and why.
563
3e6e419a
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564=head2 Temporarily fixing locale problems
565
5a964f20 566The two quickest fixes are either to render Perl silent about any
3e6e419a
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567locale inconsistencies or to run Perl under the default locale "C".
568
569Perl's moaning about locale problems can be silenced by setting the
22ff3130 570environment variable C<PERL_BADLANG> to "0" or "".
900bd440
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571This method really just sweeps the problem under the carpet: you tell
572Perl to shut up even when Perl sees that something is wrong. Do not
573be surprised if later something locale-dependent misbehaves.
3e6e419a
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574
575Perl can be run under the "C" locale by setting the environment
cb88b78e
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576variable C<LC_ALL> to "C". This method is perhaps a bit more civilized
577than the C<PERL_BADLANG> approach, but setting C<LC_ALL> (or
5a964f20
TC
578other locale variables) may affect other programs as well, not just
579Perl. In particular, external programs run from within Perl will see
3e6e419a 580these changes. If you make the new settings permanent (read on), all
f979aebc 581programs you run see the changes. See L<"ENVIRONMENT"> for
5a964f20 582the full list of relevant environment variables and L<USING LOCALES>
e05ffc7d 583for their effects in Perl. Effects in other programs are
cb88b78e 584easily deducible. For example, the variable C<LC_COLLATE> may well affect
b432a672 585your B<sort> program (or whatever the program that arranges "records"
3e6e419a
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586alphabetically in your system is called).
587
5a964f20
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588You can test out changing these variables temporarily, and if the
589new settings seem to help, put those settings into your shell startup
663d437a 590files. Consult your local documentation for the exact details. For
5a964f20 591Bourne-like shells (B<sh>, B<ksh>, B<bash>, B<zsh>):
3e6e419a
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592
593 LC_ALL=en_US.ISO8859-1
594 export LC_ALL
595
5a964f20
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596This assumes that we saw the locale "en_US.ISO8859-1" using the commands
597discussed above. We decided to try that instead of the above faulty
598locale "En_US"--and in Cshish shells (B<csh>, B<tcsh>)
3e6e419a
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599
600 setenv LC_ALL en_US.ISO8859-1
c47ff5f1 601
663d437a 602or if you have the "env" application you can do (in any shell)
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603
604 env LC_ALL=en_US.ISO8859-1 perl ...
605
5a964f20 606If you do not know what shell you have, consult your local
3e6e419a
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607helpdesk or the equivalent.
608
609=head2 Permanently fixing locale problems
610
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TC
611The slower but superior fixes are when you may be able to yourself
612fix the misconfiguration of your own environment variables. The
3e6e419a
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613mis(sing)configuration of the whole system's locales usually requires
614the help of your friendly system administrator.
615
5a964f20
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616First, see earlier in this document about L<Finding locales>. That tells
617how to find which locales are really supported--and more importantly,
618installed--on your system. In our example error message, environment
619variables affecting the locale are listed in the order of decreasing
620importance (and unset variables do not matter). Therefore, having
621LC_ALL set to "En_US" must have been the bad choice, as shown by the
622error message. First try fixing locale settings listed first.
3e6e419a 623
5a964f20
TC
624Second, if using the listed commands you see something B<exactly>
625(prefix matches do not count and case usually counts) like "En_US"
626without the quotes, then you should be okay because you are using a
627locale name that should be installed and available in your system.
4a4eefd0 628In this case, see L<Permanently fixing your system's locale configuration>.
3e6e419a 629
4a4eefd0 630=head2 Permanently fixing your system's locale configuration
3e6e419a 631
5a964f20 632This is when you see something like:
3e6e419a
JH
633
634 perl: warning: Please check that your locale settings:
635 LC_ALL = "En_US",
636 LANG = (unset)
637 are supported and installed on your system.
638
639but then cannot see that "En_US" listed by the above-mentioned
5a964f20
TC
640commands. You may see things like "en_US.ISO8859-1", but that isn't
641the same. In this case, try running under a locale
642that you can list and which somehow matches what you tried. The
3e6e419a 643rules for matching locale names are a bit vague because
e05ffc7d 644standardization is weak in this area. See again the
13a2d996 645L<Finding locales> about general rules.
3e6e419a 646
b687b08b 647=head2 Fixing system locale configuration
3e6e419a 648
5a964f20
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649Contact a system administrator (preferably your own) and report the exact
650error message you get, and ask them to read this same documentation you
651are now reading. They should be able to check whether there is something
652wrong with the locale configuration of the system. The L<Finding locales>
653section is unfortunately a bit vague about the exact commands and places
654because these things are not that standardized.
3e6e419a 655
5f05dabc
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656=head2 The localeconv function
657
39332f68 658The C<POSIX::localeconv()> function allows you to get particulars of the
14280422 659locale-dependent numeric formatting information specified by the current
a835cd47
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660underlying C<LC_NUMERIC> and C<LC_MONETARY> locales (regardless of
661whether called from within the scope of C<S<use locale>> or not). (If
662you just want the name of
39332f68 663the current locale for a particular category, use C<POSIX::setlocale()>
5a964f20 664with a single parameter--see L<The setlocale function>.)
5f05dabc
PP
665
666 use POSIX qw(locale_h);
5f05dabc
PP
667
668 # Get a reference to a hash of locale-dependent info
669 $locale_values = localeconv();
670
671 # Output sorted list of the values
672 for (sort keys %$locale_values) {
14280422 673 printf "%-20s = %s\n", $_, $locale_values->{$_}
5f05dabc
PP
674 }
675
39332f68 676C<localeconv()> takes no arguments, and returns B<a reference to> a hash.
5a964f20 677The keys of this hash are variable names for formatting, such as
502a173a 678C<decimal_point> and C<thousands_sep>. The values are the
cea6626f 679corresponding, er, values. See L<POSIX/localeconv> for a longer
502a173a
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680example listing the categories an implementation might be expected to
681provide; some provide more and others fewer. You don't need an
39332f68 682explicit C<use locale>, because C<localeconv()> always observes the
502a173a 683current locale.
5f05dabc 684
5a964f20
TC
685Here's a simple-minded example program that rewrites its command-line
686parameters as integers correctly formatted in the current locale:
5f05dabc 687
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688 use POSIX qw(locale_h);
689
690 # Get some of locale's numeric formatting parameters
691 my ($thousands_sep, $grouping) =
692 @{localeconv()}{'thousands_sep', 'grouping'};
693
694 # Apply defaults if values are missing
695 $thousands_sep = ',' unless $thousands_sep;
696
697 # grouping and mon_grouping are packed lists
698 # of small integers (characters) telling the
699 # grouping (thousand_seps and mon_thousand_seps
700 # being the group dividers) of numbers and
701 # monetary quantities. The integers' meanings:
702 # 255 means no more grouping, 0 means repeat
703 # the previous grouping, 1-254 means use that
704 # as the current grouping. Grouping goes from
705 # right to left (low to high digits). In the
706 # below we cheat slightly by never using anything
707 # else than the first grouping (whatever that is).
708 if ($grouping) {
709 @grouping = unpack("C*", $grouping);
710 } else {
711 @grouping = (3);
712 }
713
714 # Format command line params for current locale
715 for (@ARGV) {
716 $_ = int; # Chop non-integer part
717 1 while
718 s/(\d)(\d{$grouping[0]}($|$thousands_sep))/$1$thousands_sep$2/;
719 print "$_";
720 }
721 print "\n";
5f05dabc 722
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723Note that if the platform doesn't have C<LC_NUMERIC> and/or
724C<LC_MONETARY> available or enabled, the corresponding elements of the
725hash will be missing.
726
74c76037 727=head2 I18N::Langinfo
4bbcc6e8
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728
729Another interface for querying locale-dependent information is the
39332f68 730C<I18N::Langinfo::langinfo()> function, available at least in Unix-like
4bbcc6e8
JH
731systems and VMS.
732
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733The following example will import the C<langinfo()> function itself and
734three constants to be used as arguments to C<langinfo()>: a constant for
74c76037
JH
735the abbreviated first day of the week (the numbering starts from
736Sunday = 1) and two more constants for the affirmative and negative
737answers for a yes/no question in the current locale.
4bbcc6e8 738
74c76037 739 use I18N::Langinfo qw(langinfo ABDAY_1 YESSTR NOSTR);
4bbcc6e8 740
ef3087ec
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741 my ($abday_1, $yesstr, $nostr)
742 = map { langinfo } qw(ABDAY_1 YESSTR NOSTR);
4bbcc6e8 743
74c76037 744 print "$abday_1? [$yesstr/$nostr] ";
4bbcc6e8 745
74c76037
JH
746In other words, in the "C" (or English) locale the above will probably
747print something like:
748
e05ffc7d 749 Sun? [yes/no]
4bbcc6e8
JH
750
751See L<I18N::Langinfo> for more information.
752
5f05dabc
PP
753=head1 LOCALE CATEGORIES
754
5a964f20
TC
755The following subsections describe basic locale categories. Beyond these,
756some combination categories allow manipulation of more than one
757basic category at a time. See L<"ENVIRONMENT"> for a discussion of these.
5f05dabc 758
cb88b78e 759=head2 Category C<LC_COLLATE>: Collation
5f05dabc 760
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761In the scope of a S<C<use locale>> form that includes collation, Perl
762looks to the C<LC_COLLATE>
5a964f20 763environment variable to determine the application's notions on collation
b4ffc3db
TC
764(ordering) of characters. For example, "b" follows "a" in Latin
765alphabets, but where do "E<aacute>" and "E<aring>" belong? And while
f87fa335 766"color" follows "chocolate" in English, what about in traditional Spanish?
5f05dabc 767
60f0fa02 768The following collations all make sense and you may meet any of them
dbf3c4d7 769if you C<"use locale">.
60f0fa02
JH
770
771 A B C D E a b c d e
35316ca3 772 A a B b C c D d E e
60f0fa02
JH
773 a A b B c C d D e E
774 a b c d e A B C D E
775
f1cbbd6e 776Here is a code snippet to tell what "word"
5a964f20 777characters are in the current locale, in that locale's order:
5f05dabc
PP
778
779 use locale;
35316ca3 780 print +(sort grep /\w/, map { chr } 0..255), "\n";
5f05dabc 781
14280422
DD
782Compare this with the characters that you see and their order if you
783state explicitly that the locale should be ignored:
5f05dabc
PP
784
785 no locale;
35316ca3 786 print +(sort grep /\w/, map { chr } 0..255), "\n";
5f05dabc
PP
787
788This machine-native collation (which is what you get unless S<C<use
789locale>> has appeared earlier in the same block) must be used for
790sorting raw binary data, whereas the locale-dependent collation of the
b0c42ed9 791first example is useful for natural text.
5f05dabc 792
14280422
DD
793As noted in L<USING LOCALES>, C<cmp> compares according to the current
794collation locale when C<use locale> is in effect, but falls back to a
de108802 795char-by-char comparison for strings that the locale says are equal. You
39332f68 796can use C<POSIX::strcoll()> if you don't want this fall-back:
14280422
DD
797
798 use POSIX qw(strcoll);
799 $equal_in_locale =
800 !strcoll("space and case ignored", "SpaceAndCaseIgnored");
801
39332f68 802C<$equal_in_locale> will be true if the collation locale specifies a
5a964f20 803dictionary-like ordering that ignores space characters completely and
9e3a2af8 804which folds case.
14280422 805
dbf3c4d7 806Perl currently only supports single-byte locales for C<LC_COLLATE>. This means
31f05a37
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807that a UTF-8 locale likely will just give you machine-native ordering.
808Use L<Unicode::Collate> for the full implementation of the Unicode
809Collation Algorithm.
810
5a964f20 811If you have a single string that you want to check for "equality in
14280422 812locale" against several others, you might think you could gain a little
39332f68 813efficiency by using C<POSIX::strxfrm()> in conjunction with C<eq>:
14280422
DD
814
815 use POSIX qw(strxfrm);
816 $xfrm_string = strxfrm("Mixed-case string");
817 print "locale collation ignores spaces\n"
818 if $xfrm_string eq strxfrm("Mixed-casestring");
819 print "locale collation ignores hyphens\n"
820 if $xfrm_string eq strxfrm("Mixedcase string");
821 print "locale collation ignores case\n"
822 if $xfrm_string eq strxfrm("mixed-case string");
823
39332f68 824C<strxfrm()> takes a string and maps it into a transformed string for use
de108802 825in char-by-char comparisons against other transformed strings during
14280422 826collation. "Under the hood", locale-affected Perl comparison operators
39332f68
KW
827call C<strxfrm()> for both operands, then do a char-by-char
828comparison of the transformed strings. By calling C<strxfrm()> explicitly
14280422 829and using a non locale-affected comparison, the example attempts to save
5a964f20 830a couple of transformations. But in fact, it doesn't save anything: Perl
2ae324a7 831magic (see L<perlguts/Magic Variables>) creates the transformed version of a
5a964f20 832string the first time it's needed in a comparison, then keeps this version around
14280422 833in case it's needed again. An example rewritten the easy way with
e38874e2 834C<cmp> runs just about as fast. It also copes with null characters
39332f68 835embedded in strings; if you call C<strxfrm()> directly, it treats the first
5a964f20
TC
836null it finds as a terminator. don't expect the transformed strings
837it produces to be portable across systems--or even from one revision
39332f68 838of your operating system to the next. In short, don't call C<strxfrm()>
e38874e2 839directly: let Perl do it for you.
14280422 840
5a964f20 841Note: C<use locale> isn't shown in some of these examples because it isn't
dfcc8045
KW
842needed: C<strcoll()> and C<strxfrm()> are POSIX functions
843which use the standard system-supplied C<libc> functions that
844always obey the current C<LC_COLLATE> locale.
5f05dabc 845
cb88b78e 846=head2 Category C<LC_CTYPE>: Character Types
5f05dabc 847
d6ded950
KW
848In the scope of a S<C<use locale>> form that includes C<LC_CTYPE>, Perl
849obeys the C<LC_CTYPE> locale
14280422 850setting. This controls the application's notion of which characters are
ebc3223b
KW
851alphabetic, numeric, punctuation, I<etc>. This affects Perl's C<\w>
852regular expression metanotation,
f1cbbd6e 853which stands for alphanumeric characters--that is, alphabetic,
ebc3223b
KW
854numeric, and the platform's native underscore.
855(Consult L<perlre> for more information about
14280422 856regular expressions.) Thanks to C<LC_CTYPE>, depending on your locale
b4ffc3db
TC
857setting, characters like "E<aelig>", "E<eth>", "E<szlig>", and
858"E<oslash>" may be understood as C<\w> characters.
ebc3223b
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859It also affects things like C<\s>, C<\D>, and the POSIX character
860classes, like C<[[:graph:]]>. (See L<perlrecharclass> for more
861information on all these.)
5f05dabc 862
2c268ad5 863The C<LC_CTYPE> locale also provides the map used in transliterating
68dc0745 864characters between lower and uppercase. This affects the case-mapping
663d437a
KW
865functions--C<fc()>, C<lc()>, C<lcfirst()>, C<uc()>, and C<ucfirst()>;
866case-mapping
b9cc4f69
KW
867interpolation with C<\F>, C<\l>, C<\L>, C<\u>, or C<\U> in double-quoted
868strings and C<s///> substitutions; and case-independent regular expression
e38874e2
DD
869pattern matching using the C<i> modifier.
870
2da736a2 871Finally, C<LC_CTYPE> affects the (deprecated) POSIX character-class test
1d2ab946 872functions--C<POSIX::isalpha()>, C<POSIX::islower()>, and so on. For
663d437a
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873example, if you move from the "C" locale to a 7-bit ISO 646 one,
874you may find--possibly to your surprise--that C<"|"> moves from the
1d2ab946 875C<POSIX::ispunct()> class to C<POSIX::isalpha()>.
ef3087ec 876Unfortunately, this creates big problems for regular expressions. "|" still
8c6180a9
KW
877means alternation even though it matches C<\w>. Starting in v5.22, a
878warning will be raised when such a locale is switched into. More
879details are given several paragraphs further down.
5f05dabc 880
31f05a37
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881Starting in v5.20, Perl supports UTF-8 locales for C<LC_CTYPE>, but
882otherwise Perl only supports single-byte locales, such as the ISO 8859
883series. This means that wide character locales, for example for Asian
8c6180a9
KW
884languages, are not well-supported. (If the platform has the capability
885for Perl to detect such a locale, starting in Perl v5.22,
886L<Perl will warn, default enabled|warnings/Category Hierarchy>,
887using the C<locale> warning category, whenever such a locale is switched
888into.) The UTF-8 locale support is actually a
31f05a37
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889superset of POSIX locales, because it is really full Unicode behavior
890as if no locale were in effect at all (except for tainting; see
891L</SECURITY>). POSIX locales, even UTF-8 ones,
892are lacking certain concepts in Unicode, such as the idea that changing
893the case of a character could expand to be more than one character.
894Perl in a UTF-8 locale, will give you that expansion. Prior to v5.20,
895Perl treated a UTF-8 locale on some platforms like an ISO 8859-1 one,
896with some restrictions, and on other platforms more like the "C" locale.
897For releases v5.16 and v5.18, C<S<use locale 'not_characters>> could be
898used as a workaround for this (see L</Unicode and UTF-8>).
899
5d63e270 900Note that there are quite a few things that are unaffected by the
663d437a
KW
901current locale. Any literal character is the native character for the
902given platform. Hence 'A' means the character at code point 65 on ASCII
903platforms, and 193 on EBCDIC. That may or may not be an 'A' in the
904current locale, if that locale even has an 'A'.
905Similarly, all the escape sequences for particular characters,
5d63e270
KW
906C<\n> for example, always mean the platform's native one. This means,
907for example, that C<\N> in regular expressions (every character
1d2ab946 908but new-line) works on the platform character set.
5d63e270 909
8c6180a9
KW
910Starting in v5.22, Perl will by default warn when switching into a
911locale that redefines any ASCII printable character (plus C<\t> and
912C<\n>) into a different class than expected. This is unlikely to
913happen on modern locales, but can happen with the ISO 646 and other
9147-bit locales that are essentially obsolete. Things may still work,
915depending on what features of Perl are used by the program. For
916example, in the example from above where C<"|"> becomes a C<\w>, and
917there are no regular expressions where this matters, the program may
918still work properly. The warning lists all the characters that
919it can determine could be adversely affected.
920
14280422
DD
921B<Note:> A broken or malicious C<LC_CTYPE> locale definition may result
922in clearly ineligible characters being considered to be alphanumeric by
e199995e 923your application. For strict matching of (mundane) ASCII letters and
5a964f20 924digits--for example, in command strings--locale-aware applications
e199995e 925should use C<\w> with the C</a> regular expression modifier. See L<"SECURITY">.
5f05dabc 926
fee33030 927=head2 Category C<LC_NUMERIC>: Numeric Formatting
5f05dabc 928
d6ded950
KW
929After a proper C<POSIX::setlocale()> call, and within the scope of
930of a C<use locale> form that includes numerics, Perl obeys the
931C<LC_NUMERIC> locale information, which controls an application's idea
932of how numbers should be formatted for human readability.
b960a36e 933In most implementations the only effect is to
b4ffc3db 934change the character used for the decimal point--perhaps from "." to ",".
b960a36e 935The functions aren't aware of such niceties as thousands separation and
2095dafa 936so on. (See L<The localeconv function> if you care about these things.)
5a964f20 937
b960a36e
KW
938 use POSIX qw(strtod setlocale LC_NUMERIC);
939 use locale;
5f05dabc 940
b960a36e 941 setlocale LC_NUMERIC, "";
14280422 942
b960a36e 943 $n = 5/2; # Assign numeric 2.5 to $n
5f05dabc 944
b960a36e 945 $a = " $n"; # Locale-dependent conversion to string
5f05dabc 946
b960a36e 947 print "half five is $n\n"; # Locale-dependent output
5f05dabc 948
b960a36e 949 printf "half five is %g\n", $n; # Locale-dependent output
5f05dabc 950
b960a36e
KW
951 print "DECIMAL POINT IS COMMA\n"
952 if $n == (strtod("2,5"))[0]; # Locale-dependent conversion
5f05dabc 953
4bbcc6e8
JH
954See also L<I18N::Langinfo> and C<RADIXCHAR>.
955
cb88b78e 956=head2 Category C<LC_MONETARY>: Formatting of monetary amounts
5f05dabc 957
e199995e 958The C standard defines the C<LC_MONETARY> category, but not a function
5a964f20 959that is affected by its contents. (Those with experience of standards
b0c42ed9 960committees will recognize that the working group decided to punt on the
fa9b773e
KW
961issue.) Consequently, Perl essentially takes no notice of it. If you
962really want to use C<LC_MONETARY>, you can query its contents--see
e05ffc7d
KW
963L<The localeconv function>--and use the information that it returns in your
964application's own formatting of currency amounts. However, you may well
965find that the information, voluminous and complex though it may be, still
966does not quite meet your requirements: currency formatting is a hard nut
13a2d996 967to crack.
5f05dabc 968
4bbcc6e8
JH
969See also L<I18N::Langinfo> and C<CRNCYSTR>.
970
cb88b78e 971=head2 C<LC_TIME>
5f05dabc 972
39332f68 973Output produced by C<POSIX::strftime()>, which builds a formatted
5f05dabc
PP
974human-readable date/time string, is affected by the current C<LC_TIME>
975locale. Thus, in a French locale, the output produced by the C<%B>
976format element (full month name) for the first month of the year would
5a964f20 977be "janvier". Here's how to get a list of long month names in the
5f05dabc
PP
978current locale:
979
980 use POSIX qw(strftime);
14280422
DD
981 for (0..11) {
982 $long_month_name[$_] =
983 strftime("%B", 0, 0, 0, 1, $_, 96);
5f05dabc
PP
984 }
985
2619d284
KW
986Note: C<use locale> isn't needed in this example: C<strftime()> is a POSIX
987function which uses the standard system-supplied C<libc> function that
988always obeys the current C<LC_TIME> locale.
5f05dabc 989
4bbcc6e8 990See also L<I18N::Langinfo> and C<ABDAY_1>..C<ABDAY_7>, C<DAY_1>..C<DAY_7>,
2a2bf5f4 991C<ABMON_1>..C<ABMON_12>, and C<ABMON_1>..C<ABMON_12>.
4bbcc6e8 992
5f05dabc
PP
993=head2 Other categories
994
2619d284
KW
995The remaining locale categories are not currently used by Perl itself.
996But again note that things Perl interacts with may use these, including
997extensions outside the standard Perl distribution, and by the
98a6f11e 998operating system and its utilities. Note especially that the string
999value of C<$!> and the error messages given by external utilities may
1000be changed by C<LC_MESSAGES>. If you want to have portable error
265f5c4a 1001codes, use C<%!>. See L<Errno>.
14280422
DD
1002
1003=head1 SECURITY
1004
5a964f20 1005Although the main discussion of Perl security issues can be found in
14280422
DD
1006L<perlsec>, a discussion of Perl's locale handling would be incomplete
1007if it did not draw your attention to locale-dependent security issues.
5a964f20
TC
1008Locales--particularly on systems that allow unprivileged users to
1009build their own locales--are untrustworthy. A malicious (or just plain
14280422
DD
1010broken) locale can make a locale-aware application give unexpected
1011results. Here are a few possibilities:
1012
1013=over 4
1014
1015=item *
1016
1017Regular expression checks for safe file names or mail addresses using
5a964f20 1018C<\w> may be spoofed by an C<LC_CTYPE> locale that claims that
dbf3c4d7 1019characters such as C<"E<gt>"> and C<"|"> are alphanumeric.
14280422
DD
1020
1021=item *
1022
e38874e2 1023String interpolation with case-mapping, as in, say, C<$dest =
cb88b78e 1024"C:\U$name.$ext">, may produce dangerous results if a bogus C<LC_CTYPE>
e38874e2
DD
1025case-mapping table is in effect.
1026
1027=item *
1028
14280422
DD
1029A sneaky C<LC_COLLATE> locale could result in the names of students with
1030"D" grades appearing ahead of those with "A"s.
1031
1032=item *
1033
5a964f20 1034An application that takes the trouble to use information in
14280422 1035C<LC_MONETARY> may format debits as if they were credits and vice versa
5a964f20 1036if that locale has been subverted. Or it might make payments in US
14280422
DD
1037dollars instead of Hong Kong dollars.
1038
1039=item *
1040
39332f68 1041The date and day names in dates formatted by C<strftime()> could be
14280422 1042manipulated to advantage by a malicious user able to subvert the
5a964f20 1043C<LC_DATE> locale. ("Look--it says I wasn't in the building on
14280422
DD
1044Sunday.")
1045
1046=back
1047
1048Such dangers are not peculiar to the locale system: any aspect of an
5a964f20 1049application's environment which may be modified maliciously presents
14280422 1050similar challenges. Similarly, they are not specific to Perl: any
5a964f20 1051programming language that allows you to write programs that take
14280422
DD
1052account of their environment exposes you to these issues.
1053
5a964f20
TC
1054Perl cannot protect you from all possibilities shown in the
1055examples--there is no substitute for your own vigilance--but, when
14280422 1056C<use locale> is in effect, Perl uses the tainting mechanism (see
5a964f20 1057L<perlsec>) to mark string results that become locale-dependent, and
14280422 1058which may be untrustworthy in consequence. Here is a summary of the
5a964f20 1059tainting behavior of operators and functions that may be affected by
14280422
DD
1060the locale:
1061
1062=over 4
1063
551e1d92
RB
1064=item *
1065
1066B<Comparison operators> (C<lt>, C<le>, C<ge>, C<gt> and C<cmp>):
14280422
DD
1067
1068Scalar true/false (or less/equal/greater) result is never tainted.
1069
551e1d92
RB
1070=item *
1071
1d2ab946 1072B<Case-mapping interpolation> (with C<\l>, C<\L>, C<\u>, C<\U>, or C<\F>)
e38874e2 1073
d6ded950
KW
1074The result string containing interpolated material is tainted if
1075a C<use locale> form that includes C<LC_CTYPE> is in effect.
e38874e2 1076
551e1d92
RB
1077=item *
1078
1079B<Matching operator> (C<m//>):
14280422
DD
1080
1081Scalar true/false result never tainted.
1082
1d2ab946 1083All subpatterns, either delivered as a list-context result or as C<$1>
d6ded950
KW
1084I<etc>., are tainted if a C<use locale> form that includes
1085C<LC_CTYPE> is in effect, and the subpattern
63baef57
KW
1086regular expression contains a locale-dependent construct. These
1087constructs include C<\w> (to match an alphanumeric character), C<\W>
1088(non-alphanumeric character), C<\b> and C<\B> (word-boundary and
1089non-boundardy, which depend on what C<\w> and C<\W> match), C<\s>
1090(whitespace character), C<\S> (non whitespace character), C<\d> and
1091C<\D> (digits and non-digits), and the POSIX character classes, such as
1092C<[:alpha:]> (see L<perlrecharclass/POSIX Character Classes>).
1093
1094Tainting is also likely if the pattern is to be matched
1095case-insensitively (via C</i>). The exception is if all the code points
1096to be matched this way are above 255 and do not have folds under Unicode
1097rules to below 256. Tainting is not done for these because Perl
1098only uses Unicode rules for such code points, and those rules are the
1099same no matter what the current locale.
1100
1d2ab946
KW
1101The matched-pattern variables, C<$&>, C<$`> (pre-match), C<$'>
1102(post-match), and C<$+> (last match) also are tainted.
14280422 1103
551e1d92
RB
1104=item *
1105
1106B<Substitution operator> (C<s///>):
14280422 1107
e38874e2 1108Has the same behavior as the match operator. Also, the left
d6ded950
KW
1109operand of C<=~> becomes tainted when a C<use locale>
1110form that includes C<LC_CTYPE> is in effect, if modified as
66cbab2c 1111a result of a substitution based on a regular
1d2ab946
KW
1112expression match involving any of the things mentioned in the previous
1113item, or of case-mapping, such as C<\l>, C<\L>,C<\u>, C<\U>, or C<\F>.
14280422 1114
551e1d92
RB
1115=item *
1116
39332f68 1117B<Output formatting functions> (C<printf()> and C<write()>):
14280422 1118
3cf03d68
JH
1119Results are never tainted because otherwise even output from print,
1120for example C<print(1/7)>, should be tainted if C<use locale> is in
1121effect.
14280422 1122
551e1d92
RB
1123=item *
1124
39332f68 1125B<Case-mapping functions> (C<lc()>, C<lcfirst()>, C<uc()>, C<ucfirst()>):
14280422 1126
d6ded950
KW
1127Results are tainted if a C<use locale> form that includes C<LC_CTYPE> is
1128in effect.
14280422 1129
551e1d92
RB
1130=item *
1131
39332f68
KW
1132B<POSIX locale-dependent functions> (C<localeconv()>, C<strcoll()>,
1133C<strftime()>, C<strxfrm()>):
14280422
DD
1134
1135Results are never tainted.
1136
551e1d92
RB
1137=item *
1138
1d2ab946
KW
1139B<POSIX character class tests> (C<POSIX::isalnum()>,
1140C<POSIX::isalpha()>, C<POSIX::isdigit()>, C<POSIX::isgraph()>,
1141C<POSIX::islower()>, C<POSIX::isprint()>, C<POSIX::ispunct()>,
1142C<POSIX::isspace()>, C<POSIX::isupper()>, C<POSIX::isxdigit()>):
14280422
DD
1143
1144True/false results are never tainted.
1145
1146=back
1147
1148Three examples illustrate locale-dependent tainting.
1149The first program, which ignores its locale, won't run: a value taken
54310121 1150directly from the command line may not be used to name an output file
14280422
DD
1151when taint checks are enabled.
1152
1153 #/usr/local/bin/perl -T
1154 # Run with taint checking
1155
54310121 1156 # Command line sanity check omitted...
14280422
DD
1157 $tainted_output_file = shift;
1158
1159 open(F, ">$tainted_output_file")
3183d96c 1160 or warn "Open of $tainted_output_file failed: $!\n";
14280422
DD
1161
1162The program can be made to run by "laundering" the tainted value through
5a964f20
TC
1163a regular expression: the second example--which still ignores locale
1164information--runs, creating the file named on its command line
14280422
DD
1165if it can.
1166
1167 #/usr/local/bin/perl -T
1168
1169 $tainted_output_file = shift;
1170 $tainted_output_file =~ m%[\w/]+%;
1171 $untainted_output_file = $&;
1172
1173 open(F, ">$untainted_output_file")
1174 or warn "Open of $untainted_output_file failed: $!\n";
1175
5a964f20 1176Compare this with a similar but locale-aware program:
14280422
DD
1177
1178 #/usr/local/bin/perl -T
1179
1180 $tainted_output_file = shift;
1181 use locale;
1182 $tainted_output_file =~ m%[\w/]+%;
1183 $localized_output_file = $&;
1184
1185 open(F, ">$localized_output_file")
1186 or warn "Open of $localized_output_file failed: $!\n";
1187
1d2ab946 1188This third program fails to run because C<$&> is tainted: it is the result
5a964f20 1189of a match involving C<\w> while C<use locale> is in effect.
5f05dabc
PP
1190
1191=head1 ENVIRONMENT
1192
1193=over 12
1194
ee1ec05f
KW
1195=item PERL_SKIP_LOCALE_INIT
1196
c5c88224
KW
1197This environment variable, available starting in Perl v5.20, if set
1198(to any value), tells Perl to not use the rest of the
ee1ec05f
KW
1199environment variables to initialize with. Instead, Perl uses whatever
1200the current locale settings are. This is particularly useful in
1201embedded environments, see
1202L<perlembed/Using embedded Perl with POSIX locales>.
1203
5f05dabc
PP
1204=item PERL_BADLANG
1205
14280422 1206A string that can suppress Perl's warning about failed locale settings
54310121 1207at startup. Failure can occur if the locale support in the operating
5a964f20 1208system is lacking (broken) in some way--or if you mistyped the name of
900bd440 1209a locale when you set up your environment. If this environment
22ff3130
HS
1210variable is absent, or has a value other than "0" or "", Perl will
1211complain about locale setting failures.
5f05dabc 1212
cb88b78e 1213B<NOTE>: C<PERL_BADLANG> only gives you a way to hide the warning message.
14280422
DD
1214The message tells about some problem in your system's locale support,
1215and you should investigate what the problem is.
5f05dabc
PP
1216
1217=back
1218
1219The following environment variables are not specific to Perl: They are
39332f68 1220part of the standardized (ISO C, XPG4, POSIX 1.c) C<setlocale()> method
b385bb4d
KW
1221for controlling an application's opinion on data. Windows is non-POSIX,
1222but Perl arranges for the following to work as described anyway.
65ebb059
KW
1223If the locale given by an environment variable is not valid, Perl tries
1224the next lower one in priority. If none are valid, on Windows, the
1225system default locale is then tried. If all else fails, the C<"C">
1226locale is used. If even that doesn't work, something is badly broken,
c5e9a8e7 1227but Perl tries to forge ahead with whatever the locale settings might
65ebb059 1228be.
5f05dabc
PP
1229
1230=over 12
1231
cb88b78e 1232=item C<LC_ALL>
5f05dabc 1233
5a964f20 1234C<LC_ALL> is the "override-all" locale environment variable. If
5f05dabc
PP
1235set, it overrides all the rest of the locale environment variables.
1236
cb88b78e 1237=item C<LANGUAGE>
528d65ad
JH
1238
1239B<NOTE>: C<LANGUAGE> is a GNU extension, it affects you only if you
1240are using the GNU libc. This is the case if you are using e.g. Linux.
e1020413 1241If you are using "commercial" Unixes you are most probably I<not>
22b6f60d
JH
1242using GNU libc and you can ignore C<LANGUAGE>.
1243
1244However, in the case you are using C<LANGUAGE>: it affects the
1245language of informational, warning, and error messages output by
1246commands (in other words, it's like C<LC_MESSAGES>) but it has higher
96090e4f 1247priority than C<LC_ALL>. Moreover, it's not a single value but
22b6f60d
JH
1248instead a "path" (":"-separated list) of I<languages> (not locales).
1249See the GNU C<gettext> library documentation for more information.
528d65ad 1250
cb88b78e 1251=item C<LC_CTYPE>.
5f05dabc
PP
1252
1253In the absence of C<LC_ALL>, C<LC_CTYPE> chooses the character type
1254locale. In the absence of both C<LC_ALL> and C<LC_CTYPE>, C<LANG>
1255chooses the character type locale.
1256
cb88b78e 1257=item C<LC_COLLATE>
5f05dabc 1258
14280422
DD
1259In the absence of C<LC_ALL>, C<LC_COLLATE> chooses the collation
1260(sorting) locale. In the absence of both C<LC_ALL> and C<LC_COLLATE>,
1261C<LANG> chooses the collation locale.
5f05dabc 1262
cb88b78e 1263=item C<LC_MONETARY>
5f05dabc 1264
14280422
DD
1265In the absence of C<LC_ALL>, C<LC_MONETARY> chooses the monetary
1266formatting locale. In the absence of both C<LC_ALL> and C<LC_MONETARY>,
1267C<LANG> chooses the monetary formatting locale.
5f05dabc 1268
cb88b78e 1269=item C<LC_NUMERIC>
5f05dabc
PP
1270
1271In the absence of C<LC_ALL>, C<LC_NUMERIC> chooses the numeric format
1272locale. In the absence of both C<LC_ALL> and C<LC_NUMERIC>, C<LANG>
1273chooses the numeric format.
1274
cb88b78e 1275=item C<LC_TIME>
5f05dabc 1276
14280422
DD
1277In the absence of C<LC_ALL>, C<LC_TIME> chooses the date and time
1278formatting locale. In the absence of both C<LC_ALL> and C<LC_TIME>,
1279C<LANG> chooses the date and time formatting locale.
5f05dabc 1280
cb88b78e 1281=item C<LANG>
5f05dabc 1282
14280422
DD
1283C<LANG> is the "catch-all" locale environment variable. If it is set, it
1284is used as the last resort after the overall C<LC_ALL> and the
cb88b78e 1285category-specific C<LC_I<foo>>
5f05dabc
PP
1286
1287=back
1288
7e4353e9
RGS
1289=head2 Examples
1290
cb88b78e 1291The C<LC_NUMERIC> controls the numeric output:
7e4353e9 1292
ef3087ec
KW
1293 use locale;
1294 use POSIX qw(locale_h); # Imports setlocale() and the LC_ constants.
1295 setlocale(LC_NUMERIC, "fr_FR") or die "Pardon";
1296 printf "%g\n", 1.23; # If the "fr_FR" succeeded, probably shows 1,23.
7e4353e9 1297
39332f68 1298and also how strings are parsed by C<POSIX::strtod()> as numbers:
7e4353e9 1299
ef3087ec
KW
1300 use locale;
1301 use POSIX qw(locale_h strtod);
1302 setlocale(LC_NUMERIC, "de_DE") or die "Entschuldigung";
1303 my $x = strtod("2,34") + 5;
1304 print $x, "\n"; # Probably shows 7,34.
7e4353e9 1305
5f05dabc
PP
1306=head1 NOTES
1307
b960a36e
KW
1308=head2 String C<eval> and C<LC_NUMERIC>
1309
1310A string L<eval|perlfunc/eval EXPR> parses its expression as standard
1311Perl. It is therefore expecting the decimal point to be a dot. If
1312C<LC_NUMERIC> is set to have this be a comma instead, the parsing will
1313be confused, perhaps silently.
1314
1315 use locale;
1316 use POSIX qw(locale_h);
1317 setlocale(LC_NUMERIC, "fr_FR") or die "Pardon";
1318 my $a = 1.2;
1319 print eval "$a + 1.5";
1320 print "\n";
1321
1322prints C<13,5>. This is because in that locale, the comma is the
1323decimal point character. The C<eval> thus expands to:
1324
1325 eval "1,2 + 1.5"
1326
1327and the result is not what you likely expected. No warnings are
1328generated. If you do string C<eval>'s within the scope of
1329S<C<use locale>>, you should instead change the C<eval> line to do
1330something like:
1331
1332 print eval "no locale; $a + 1.5";
1333
1334This prints C<2.7>.
1335
d6ded950
KW
1336You could also exclude C<LC_NUMERIC>, if you don't need it, by
1337
1338 use locale ':!numeric';
1339
5f05dabc
PP
1340=head2 Backward compatibility
1341
b0c42ed9 1342Versions of Perl prior to 5.004 B<mostly> ignored locale information,
5a964f20
TC
1343generally behaving as if something similar to the C<"C"> locale were
1344always in force, even if the program environment suggested otherwise
1345(see L<The setlocale function>). By default, Perl still behaves this
1346way for backward compatibility. If you want a Perl application to pay
1347attention to locale information, you B<must> use the S<C<use locale>>
d6ded950 1348pragma (see L<The "use locale" pragma>) or, in the unlikely event
062ca197 1349that you want to do so for just pattern matching, the
70709c68
KW
1350C</l> regular expression modifier (see L<perlre/Character set
1351modifiers>) to instruct it to do so.
b0c42ed9
JH
1352
1353Versions of Perl from 5.002 to 5.003 did use the C<LC_CTYPE>
5a964f20
TC
1354information if available; that is, C<\w> did understand what
1355were the letters according to the locale environment variables.
b0c42ed9
JH
1356The problem was that the user had no control over the feature:
1357if the C library supported locales, Perl used them.
1358
1359=head2 I18N:Collate obsolete
1360
5a964f20 1361In versions of Perl prior to 5.004, per-locale collation was possible
b0c42ed9
JH
1362using the C<I18N::Collate> library module. This module is now mildly
1363obsolete and should be avoided in new applications. The C<LC_COLLATE>
1364functionality is now integrated into the Perl core language: One can
1365use locale-specific scalar data completely normally with C<use locale>,
1366so there is no longer any need to juggle with the scalar references of
1367C<I18N::Collate>.
5f05dabc 1368
14280422 1369=head2 Sort speed and memory use impacts
5f05dabc
PP
1370
1371Comparing and sorting by locale is usually slower than the default
14280422
DD
1372sorting; slow-downs of two to four times have been observed. It will
1373also consume more memory: once a Perl scalar variable has participated
1374in any string comparison or sorting operation obeying the locale
1375collation rules, it will take 3-15 times more memory than before. (The
1376exact multiplier depends on the string's contents, the operating system
1377and the locale.) These downsides are dictated more by the operating
1378system's implementation of the locale system than by Perl.
5f05dabc 1379
5f05dabc
PP
1380=head2 Freely available locale definitions
1381
66cbab2c
KW
1382The Unicode CLDR project extracts the POSIX portion of many of its
1383locales, available at
1384
1385 http://unicode.org/Public/cldr/latest/
1386
08d7a6b2
LB
1387There is a large collection of locale definitions at:
1388
1389 http://std.dkuug.dk/i18n/WG15-collection/locales/
1390
1391You should be aware that it is
14280422 1392unsupported, and is not claimed to be fit for any purpose. If your
5a964f20 1393system allows installation of arbitrary locales, you may find the
14280422
DD
1394definitions useful as they are, or as a basis for the development of
1395your own locales.
5f05dabc 1396
14280422 1397=head2 I18n and l10n
5f05dabc 1398
b0c42ed9
JH
1399"Internationalization" is often abbreviated as B<i18n> because its first
1400and last letters are separated by eighteen others. (You may guess why
1401the internalin ... internaliti ... i18n tends to get abbreviated.) In
1402the same way, "localization" is often abbreviated to B<l10n>.
14280422
DD
1403
1404=head2 An imperfect standard
1405
1406Internationalization, as defined in the C and POSIX standards, can be
1407criticized as incomplete, ungainly, and having too large a granularity.
1408(Locales apply to a whole process, when it would arguably be more useful
1409to have them apply to a single thread, window group, or whatever.) They
1410also have a tendency, like standards groups, to divide the world into
1411nations, when we all know that the world can equally well be divided
e199995e 1412into bankers, bikers, gamers, and so on.
5f05dabc 1413
b310b053
JH
1414=head1 Unicode and UTF-8
1415
7ee2ae1e 1416The support of Unicode is new starting from Perl version v5.6, and more fully
31f05a37
KW
1417implemented in versions v5.8 and later. See L<perluniintro>.
1418
1419Starting in Perl v5.20, UTF-8 locales are supported in Perl, except for
1420C<LC_COLLATE> (use L<Unicode::Collate> instead). If you have Perl v5.16
1421or v5.18 and can't upgrade, you can use
66cbab2c
KW
1422
1423 use locale ':not_characters';
1424
1425When this form of the pragma is used, only the non-character portions of
1426locales are used by Perl, for example C<LC_NUMERIC>. Perl assumes that
1427you have translated all the characters it is to operate on into Unicode
1428(actually the platform's native character set (ASCII or EBCDIC) plus
1429Unicode). For data in files, this can conveniently be done by also
1430specifying
1431
1432 use open ':locale';
1433
1434This pragma arranges for all inputs from files to be translated into
1435Unicode from the current locale as specified in the environment (see
1436L</ENVIRONMENT>), and all outputs to files to be translated back
1437into the locale. (See L<open>). On a per-filehandle basis, you can
1438instead use the L<PerlIO::locale> module, or the L<Encode::Locale>
1439module, both available from CPAN. The latter module also has methods to
1440ease the handling of C<ARGV> and environment variables, and can be used
31f05a37 1441on individual strings. If you know that all your locales will be
66cbab2c
KW
1442UTF-8, as many are these days, you can use the L<B<-C>|perlrun/-C>
1443command line switch.
1444
1445This form of the pragma allows essentially seamless handling of locales
31f05a37
KW
1446with Unicode. The collation order will be by Unicode code point order.
1447It is strongly
66cbab2c
KW
1448recommended that when you need to order and sort strings that you use
1449the standard module L<Unicode::Collate> which gives much better results
1450in many instances than you can get with the old-style locale handling.
1451
31f05a37
KW
1452All the modules and switches just described can be used in v5.20 with
1453just plain C<use locale>, and, should the input locales not be UTF-8,
1454you'll get the less than ideal behavior, described below, that you get
1455with pre-v5.16 Perls, or when you use the locale pragma without the
1456C<:not_characters> parameter in v5.16 and v5.18. If you are using
1457exclusively UTF-8 locales in v5.20 and higher, the rest of this section
1458does not apply to you.
1459
1460There are two cases, multi-byte and single-byte locales. First
1461multi-byte:
1462
1463The only multi-byte (or wide character) locale that Perl is ever likely
1464to support is UTF-8. This is due to the difficulty of implementation,
1465the fact that high quality UTF-8 locales are now published for every
1466area of the world (L<http://unicode.org/Public/cldr/latest/>), and that
1467failing all that you can use the L<Encode> module to translate to/from
1468your locale. So, you'll have to do one of those things if you're using
1469one of these locales, such as Big5 or Shift JIS. For UTF-8 locales, in
1470Perls (pre v5.20) that don't have full UTF-8 locale support, they may
1471work reasonably well (depending on your C library implementation)
1472simply because both
dc4bfc4b
KW
1473they and Perl store characters that take up multiple bytes the same way.
1474However, some, if not most, C library implementations may not process
1475the characters in the upper half of the Latin-1 range (128 - 255)
cb88b78e 1476properly under C<LC_CTYPE>. To see if a character is a particular type
dc4bfc4b
KW
1477under a locale, Perl uses the functions like C<isalnum()>. Your C
1478library may not work for UTF-8 locales with those functions, instead
dbf3c4d7
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1479only working under the newer wide library functions like C<iswalnum()>,
1480which Perl does not use.
1481These multi-byte locales are treated like single-byte locales, and will
1482have the restrictions described below. Starting in Perl v5.22 a warning
1483message is raised when Perl detects a multi-byte locale that it doesn't
1484fully support.
e199995e 1485
31f05a37 1486For single-byte locales,
e199995e 1487Perl generally takes the tack to use locale rules on code points that can fit
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KW
1488in a single byte, and Unicode rules for those that can't (though this
1489isn't uniformly applied, see the note at the end of this section). This
1490prevents many problems in locales that aren't UTF-8. Suppose the locale
1491is ISO8859-7, Greek. The character at 0xD7 there is a capital Chi. But
1492in the ISO8859-1 locale, Latin1, it is a multiplication sign. The POSIX
1493regular expression character class C<[[:alpha:]]> will magically match
14940xD7 in the Greek locale but not in the Latin one.
e199995e 1495
1d2ab946 1496However, there are places where this breaks down. Certain Perl constructs are
b4ffc3db
TC
1497for Unicode only, such as C<\p{Alpha}>. They assume that 0xD7 always has its
1498Unicode meaning (or the equivalent on EBCDIC platforms). Since Latin1 is a
1499subset of Unicode and 0xD7 is the multiplication sign in both Latin1 and
1500Unicode, C<\p{Alpha}> will never match it, regardless of locale. A similar
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1501issue occurs with C<\N{...}>. Prior to v5.20, It is therefore a bad
1502idea to use C<\p{}> or
66cbab2c 1503C<\N{}> under plain C<use locale>--I<unless> you can guarantee that the
dbf3c4d7 1504locale will be ISO8859-1. Use POSIX character classes instead.
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1505
1506Another problem with this approach is that operations that cross the
1507single byte/multiple byte boundary are not well-defined, and so are
4a70680a 1508disallowed. (This boundary is between the codepoints at 255/256.)
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KW
1509For example, lower casing LATIN CAPITAL LETTER Y WITH DIAERESIS (U+0178)
1510should return LATIN SMALL LETTER Y WITH DIAERESIS (U+00FF). But in the
1511Greek locale, for example, there is no character at 0xFF, and Perl
1512has no way of knowing what the character at 0xFF is really supposed to
1513represent. Thus it disallows the operation. In this mode, the
1514lowercase of U+0178 is itself.
1515
1516The same problems ensue if you enable automatic UTF-8-ification of your
e199995e 1517standard file handles, default C<open()> layer, and C<@ARGV> on non-ISO8859-1,
b4ffc3db
TC
1518non-UTF-8 locales (by using either the B<-C> command line switch or the
1519C<PERL_UNICODE> environment variable; see L<perlrun>).
1520Things are read in as UTF-8, which would normally imply a Unicode
1521interpretation, but the presence of a locale causes them to be interpreted
1522in that locale instead. For example, a 0xD7 code point in the Unicode
1523input, which should mean the multiplication sign, won't be interpreted by
66cbab2c 1524Perl that way under the Greek locale. This is not a problem
b4ffc3db 1525I<provided> you make certain that all locales will always and only be either
66cbab2c 1526an ISO8859-1, or, if you don't have a deficient C library, a UTF-8 locale.
b4ffc3db 1527
1d2ab946
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1528Still another problem is that this approach can lead to two code
1529points meaning the same character. Thus in a Greek locale, both U+03A7
1530and U+00D7 are GREEK CAPITAL LETTER CHI.
1531
613abc6d
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1532Because of all these problems, starting in v5.22, Perl will raise a
1533warning if a multi-byte (hence Unicode) code point is used when a
1534single-byte locale is in effect. (Although it doesn't check for this if
1535doing so would unreasonably slow execution down.)
1536
b4ffc3db
TC
1537Vendor locales are notoriously buggy, and it is difficult for Perl to test
1538its locale-handling code because this interacts with code that Perl has no
1539control over; therefore the locale-handling code in Perl may be buggy as
66cbab2c
KW
1540well. (However, the Unicode-supplied locales should be better, and
1541there is a feed back mechanism to correct any problems. See
1542L</Freely available locale definitions>.)
1543
7ee2ae1e 1544If you have Perl v5.16, the problems mentioned above go away if you use
66cbab2c 1545the C<:not_characters> parameter to the locale pragma (except for vendor
7ee2ae1e 1546bugs in the non-character portions). If you don't have v5.16, and you
66cbab2c
KW
1547I<do> have locales that work, using them may be worthwhile for certain
1548specific purposes, as long as you keep in mind the gotchas already
1549mentioned. For example, if the collation for your locales works, it
1550runs faster under locales than under L<Unicode::Collate>; and you gain
1551access to such things as the local currency symbol and the names of the
7ee2ae1e 1552months and days of the week. (But to hammer home the point, in v5.16,
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1553you get this access without the downsides of locales by using the
1554C<:not_characters> form of the pragma.)
1555
1556Note: The policy of using locale rules for code points that can fit in a
1557byte, and Unicode rules for those that can't is not uniformly applied.
7ee2ae1e 1558Pre-v5.12, it was somewhat haphazard; in v5.12 it was applied fairly
66cbab2c 1559consistently to regular expression matching except for bracketed
7ee2ae1e 1560character classes; in v5.14 it was extended to all regex matches; and in
663d437a 1561v5.16 to the casing operations such as C<\L> and C<uc()>. For
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1562collation, in all releases so far, the system's C<strxfrm()> function is
1563called, and whatever it does is what you get.
b310b053 1564
5f05dabc
PP
1565=head1 BUGS
1566
1567=head2 Broken systems
1568
5a964f20 1569In certain systems, the operating system's locale support
2bdf8add 1570is broken and cannot be fixed or used by Perl. Such deficiencies can
b4ffc3db 1571and will result in mysterious hangs and/or Perl core dumps when
2bdf8add 1572C<use locale> is in effect. When confronted with such a system,
7f2de2d2 1573please report in excruciating detail to <F<perlbug@perl.org>>, and
b4ffc3db 1574also contact your vendor: bug fixes may exist for these problems
2bdf8add 1575in your operating system. Sometimes such bug fixes are called an
83fb1bf0
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1576operating system upgrade. If you have the source for Perl, include in
1577the perlbug email the output of the test described above in L</Testing
1578for broken locales>.
5f05dabc
PP
1579
1580=head1 SEE ALSO
1581
b310b053
JH
1582L<I18N::Langinfo>, L<perluniintro>, L<perlunicode>, L<open>,
1583L<POSIX/isalnum>, L<POSIX/isalpha>,
4bbcc6e8
JH
1584L<POSIX/isdigit>, L<POSIX/isgraph>, L<POSIX/islower>,
1585L<POSIX/isprint>, L<POSIX/ispunct>, L<POSIX/isspace>,
1586L<POSIX/isupper>, L<POSIX/isxdigit>, L<POSIX/localeconv>,
1587L<POSIX/setlocale>, L<POSIX/strcoll>, L<POSIX/strftime>,
1588L<POSIX/strtod>, L<POSIX/strxfrm>.
5f05dabc 1589
ccd65d51
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1590For special considerations when Perl is embedded in a C program,
1591see L<perlembed/Using embedded Perl with POSIX locales>.
1592
5f05dabc
PP
1593=head1 HISTORY
1594
b0c42ed9 1595Jarkko Hietaniemi's original F<perli18n.pod> heavily hacked by Dominic
5a964f20 1596Dunlop, assisted by the perl5-porters. Prose worked over a bit by
c052850d 1597Tom Christiansen, and updated by Perl 5 porters.