=head1 DESCRIPTION
-Perl supports language-specific notions of data such as "is this a
-letter", "what is the uppercase equivalent of this letter", and "which
-of these letters comes first". These are important issues, especially
-for languages other than English - but also for English: it would be
-very naE<iuml>ve to think that C<A-Za-z> defines all the "letters". Perl
-is also aware that some character other than '.' may be preferred as a
-decimal point, and that output date representations may be
-language-specific. The process of making an application take account of
-its users' preferences in such matters is called B<internationalization>
-(often abbreviated as B<i18n>); telling such an application about a
-particular set of preferences is known as B<localization> (B<l10n>).
+Perl supports language-specific notions of data such as "is this
+a letter", "what is the uppercase equivalent of this letter", and
+"which of these letters comes first". These are important issues,
+especially for languages other than English--but also for English: it
+would be naE<iuml>ve to imagine that C<A-Za-z> defines all the "letters"
+needed to write in English. Perl is also aware that some character other
+than '.' may be preferred as a decimal point, and that output date
+representations may be language-specific. The process of making an
+application take account of its users' preferences in such matters is
+called B<internationalization> (often abbreviated as B<i18n>); telling
+such an application about a particular set of preferences is known as
+B<localization> (B<l10n>).
Perl can understand language-specific data via the standardized (ISO C,
XPG4, POSIX 1.c) method called "the locale system". The locale system is
several environment variables.
B<NOTE>: This feature is new in Perl 5.004, and does not apply unless an
-application specifically requests it - see L<Backward compatibility>.
+application specifically requests it--see L<Backward compatibility>.
The one exception is that write() now B<always> uses the current locale
- see L<"NOTES">.
=head1 PREPARING TO USE LOCALES
-If Perl applications are to be able to understand and present your data
+If Perl applications are to understand and present your data
correctly according a locale of your choice, B<all> of the following
must be true:
=item *
-B<Definitions for the locales which you use must be installed>. You, or
+B<Definitions for locales that you use must be installed>. You, or
your system administrator, must make sure that this is the case. The
available locales, the location in which they are kept, and the manner
-in which they are installed, vary from system to system. Some systems
-provide only a few, hard-wired, locales, and do not allow more to be
-added; others allow you to add "canned" locales provided by the system
-supplier; still others allow you or the system administrator to define
+in which they are installed all vary from system to system. Some systems
+provide only a few, hard-wired locales and do not allow more to be
+added. Others allow you to add "canned" locales provided by the system
+supplier. Still others allow you or the system administrator to define
and add arbitrary locales. (You may have to ask your supplier to
-provide canned locales which are not delivered with your operating
+provide canned locales that are not delivered with your operating
system.) Read your system documentation for further illumination.
=item *
=item *
B<The locale-determining environment variables (see L<"ENVIRONMENT">)
-must be correctly set up>, either by yourself, or by the person who set
-up your system account, at the time the application is started.
+must be correctly set up> at the time the application is started, either
+by yourself or by whoever set up your system account.
=item *
B<The comparison operators> (C<lt>, C<le>, C<cmp>, C<ge>, and C<gt>) and
the POSIX string collation functions strcoll() and strxfrm() use
-C<LC_COLLATE>. sort() is also affected if it is used without an
-explicit comparison function because it uses C<cmp> by default.
+C<LC_COLLATE>. sort() is also affected if used without an
+explicit comparison function, because it uses C<cmp> by default.
-B<Note:> C<eq> and C<ne> are unaffected by the locale: they always
-perform a byte-by-byte comparison of their scalar operands. What's
+B<Note:> C<eq> and C<ne> are unaffected by locale: they always
+perform a char-by-char comparison of their scalar operands. What's
more, if C<cmp> finds that its operands are equal according to the
collation sequence specified by the current locale, it goes on to
-perform a byte-by-byte comparison, and only returns I<0> (equal) if the
-operands are bit-for-bit identical. If you really want to know whether
-two strings - which C<eq> and C<cmp> may consider different - are equal
+perform a char-by-char comparison, and only returns I<0> (equal) if the
+operands are char-for-char identical. If you really want to know whether
+two strings--which C<eq> and C<cmp> may consider different--are equal
as far as collation in the locale is concerned, see the discussion in
L<Category LC_COLLATE: Collation>.
=back
-C<LC_COLLATE>, C<LC_CTYPE>, and so on, are discussed further in L<LOCALE
-CATEGORIES>.
+C<LC_COLLATE>, C<LC_CTYPE>, and so on, are discussed further in
+L<LOCALE CATEGORIES>.
-The default behavior returns with S<C<no locale>> or on reaching the
-end of the enclosing block.
+The default behavior is restored with the S<C<no locale>> pragma, or
+upon reaching the end of block enclosing C<use locale>.
-Note that the string result of any operation that uses locale
+The string result of any operation that uses locale
information is tainted, as it is possible for a locale to be
untrustworthy. See L<"SECURITY">.
hints on the naming of locales: not all systems name locales as in the
example.
-If no second argument is provided, the function returns a string naming
-the current locale for the category. You can use this value as the
-second argument in a subsequent call to setlocale(). If a second
-argument is given and it corresponds to a valid locale, the locale for
-the category is set to that value, and the function returns the
-now-current locale value. You can use this in a subsequent call to
-setlocale(). (In some implementations, the return value may sometimes
-differ from the value you gave as the second argument - think of it as
-an alias for the value that you gave.)
+If no second argument is provided and the category is something else
+than LC_ALL, the function returns a string naming the current locale
+for the category. You can use this value as the second argument in a
+subsequent call to setlocale().
+
+If no second argument is provided and the category is LC_ALL, the
+result is implementation-dependent. It may be a string of
+concatenated locales names (separator also implementation-dependent)
+or a single locale name. Please consult your L<setlocale(3)> for
+details.
+
+If a second argument is given and it corresponds to a valid locale,
+the locale for the category is set to that value, and the function
+returns the now-current locale value. You can then use this in yet
+another call to setlocale(). (In some implementations, the return
+value may sometimes differ from the value you gave as the second
+argument--think of it as an alias for the value you gave.)
As the example shows, if the second argument is an empty string, the
category's locale is returned to the default specified by the
corresponding environment variables. Generally, this results in a
-return to the default which was in force when Perl started up: changes
+return to the default that was in force when Perl started up: changes
to the environment made by the application after startup may or may not
-be noticed, depending on the implementation of your system's C library.
+be noticed, depending on your system's C library.
If the second argument does not correspond to a valid locale, the locale
for the category is not changed, and the function returns I<undef>.
For further information about the categories, consult L<setlocale(3)>.
-For the locales available in your system, also consult L<setlocale(3)>
-and see whether it leads you to the list of the available locales
-(search for the I<SEE ALSO> section). If that fails, try the following
-command lines:
+
+=head2 Finding locales
+
+For locales available in your system, consult also L<setlocale(3)> to
+see whether it leads to the list of available locales (search for the
+I<SEE ALSO> section). If that fails, try the following command lines:
locale -a
ls /usr/lib/nls
+ ls /usr/share/locale
+
and see whether they list something resembling these
en_US.ISO8859-1 de_DE.ISO8859-1 ru_RU.ISO8859-5
+ en_US.iso88591 de_DE.iso88591 ru_RU.iso88595
en_US de_DE ru_RU
en de ru
english german russian
english.iso88591 german.iso88591 russian.iso88595
+ english.roman8 russian.koi8r
Sadly, even though the calling interface for setlocale() has been
-standardized, the names of the locales and the directories where
-the configuration is, have not. The basic form of the name is
-I<language_country/territory>B<.>I<codeset>, but the
-latter parts are not always present.
+standardized, names of locales and the directories where the
+configuration resides have not been. The basic form of the name is
+I<language_territory>B<.>I<codeset>, but the latter parts after
+I<language> are not always present. The I<language> and I<country>
+are usually from the standards B<ISO 3166> and B<ISO 639>, the
+two-letter abbreviations for the countries and the languages of the
+world, respectively. The I<codeset> part often mentions some B<ISO
+8859> character set, the Latin codesets. For example, C<ISO 8859-1>
+is the so-called "Western European codeset" that can be used to encode
+most Western European languages adequately. Again, there are several
+ways to write even the name of that one standard. Lamentably.
Two special locales are worth particular mention: "C" and "POSIX".
Currently these are effectively the same locale: the difference is
-mainly that the first one is defined by the C standard and the second by
-the POSIX standard. What they define is the B<default locale> in which
+mainly that the first one is defined by the C standard, the second by
+the POSIX standard. They define the B<default locale> in which
every program starts in the absence of locale information in its
-environment. (The default default locale, if you will.) Its language
+environment. (The I<default> default locale, if you will.) Its language
is (American) English and its character codeset ASCII.
B<NOTE>: Not all systems have the "POSIX" locale (not all systems are
POSIX-conformant), so use "C" when you need explicitly to specify this
default locale.
+=head2 LOCALE PROBLEMS
+
+You may encounter the following warning message at Perl startup:
+
+ perl: warning: Setting locale failed.
+ perl: warning: Please check that your locale settings:
+ LC_ALL = "En_US",
+ LANG = (unset)
+ are supported and installed on your system.
+ perl: warning: Falling back to the standard locale ("C").
+
+This means that your locale settings had LC_ALL set to "En_US" and
+LANG exists but has no value. Perl tried to believe you but could not.
+Instead, Perl gave up and fell back to the "C" locale, the default locale
+that is supposed to work no matter what. This usually means your locale
+settings were wrong, they mention locales your system has never heard
+of, or the locale installation in your system has problems (for example,
+some system files are broken or missing). There are quick and temporary
+fixes to these problems, as well as more thorough and lasting fixes.
+
+=head2 Temporarily fixing locale problems
+
+The two quickest fixes are either to render Perl silent about any
+locale inconsistencies or to run Perl under the default locale "C".
+
+Perl's moaning about locale problems can be silenced by setting the
+environment variable PERL_BADLANG to a zero value, for example "0".
+This method really just sweeps the problem under the carpet: you tell
+Perl to shut up even when Perl sees that something is wrong. Do not
+be surprised if later something locale-dependent misbehaves.
+
+Perl can be run under the "C" locale by setting the environment
+variable LC_ALL to "C". This method is perhaps a bit more civilized
+than the PERL_BADLANG approach, but setting LC_ALL (or
+other locale variables) may affect other programs as well, not just
+Perl. In particular, external programs run from within Perl will see
+these changes. If you make the new settings permanent (read on), all
+programs you run see the changes. See L<ENVIRONMENT> for
+the full list of relevant environment variables and L<USING LOCALES>
+for their effects in Perl. Effects in other programs are
+easily deducible. For example, the variable LC_COLLATE may well affect
+your B<sort> program (or whatever the program that arranges `records'
+alphabetically in your system is called).
+
+You can test out changing these variables temporarily, and if the
+new settings seem to help, put those settings into your shell startup
+files. Consult your local documentation for the exact details. For in
+Bourne-like shells (B<sh>, B<ksh>, B<bash>, B<zsh>):
+
+ LC_ALL=en_US.ISO8859-1
+ export LC_ALL
+
+This assumes that we saw the locale "en_US.ISO8859-1" using the commands
+discussed above. We decided to try that instead of the above faulty
+locale "En_US"--and in Cshish shells (B<csh>, B<tcsh>)
+
+ setenv LC_ALL en_US.ISO8859-1
+
+or if you have the "env" application you can do in any shell
+
+ env LC_ALL=en_US.ISO8859-1 perl ...
+
+If you do not know what shell you have, consult your local
+helpdesk or the equivalent.
+
+=head2 Permanently fixing locale problems
+
+The slower but superior fixes are when you may be able to yourself
+fix the misconfiguration of your own environment variables. The
+mis(sing)configuration of the whole system's locales usually requires
+the help of your friendly system administrator.
+
+First, see earlier in this document about L<Finding locales>. That tells
+how to find which locales are really supported--and more importantly,
+installed--on your system. In our example error message, environment
+variables affecting the locale are listed in the order of decreasing
+importance (and unset variables do not matter). Therefore, having
+LC_ALL set to "En_US" must have been the bad choice, as shown by the
+error message. First try fixing locale settings listed first.
+
+Second, if using the listed commands you see something B<exactly>
+(prefix matches do not count and case usually counts) like "En_US"
+without the quotes, then you should be okay because you are using a
+locale name that should be installed and available in your system.
+In this case, see L<Permanently fixing your system's locale configuration>.
+
+=head2 Permanently fixing your system's locale configuration
+
+This is when you see something like:
+
+ perl: warning: Please check that your locale settings:
+ LC_ALL = "En_US",
+ LANG = (unset)
+ are supported and installed on your system.
+
+but then cannot see that "En_US" listed by the above-mentioned
+commands. You may see things like "en_US.ISO8859-1", but that isn't
+the same. In this case, try running under a locale
+that you can list and which somehow matches what you tried. The
+rules for matching locale names are a bit vague because
+standardization is weak in this area. See again the
+L<Finding locales> about general rules.
+
+=head2 Fixing system locale configuration
+
+Contact a system administrator (preferably your own) and report the exact
+error message you get, and ask them to read this same documentation you
+are now reading. They should be able to check whether there is something
+wrong with the locale configuration of the system. The L<Finding locales>
+section is unfortunately a bit vague about the exact commands and places
+because these things are not that standardized.
+
=head2 The localeconv function
The POSIX::localeconv() function allows you to get particulars of the
locale-dependent numeric formatting information specified by the current
C<LC_NUMERIC> and C<LC_MONETARY> locales. (If you just want the name of
the current locale for a particular category, use POSIX::setlocale()
-with a single parameter - see L<The setlocale function>.)
+with a single parameter--see L<The setlocale function>.)
use POSIX qw(locale_h);
}
localeconv() takes no arguments, and returns B<a reference to> a hash.
-The keys of this hash are formatting variable names such as
-C<decimal_point> and C<thousands_sep>; the values are the corresponding
-values. See L<POSIX (3)/localeconv> for a longer example, which lists
-all the categories an implementation might be expected to provide; some
-provide more and others fewer, however. Note that you don't need C<use
-locale>: as a function with the job of querying the locale, localeconv()
-always observes the current locale.
+The keys of this hash are variable names for formatting, such as
+C<decimal_point> and C<thousands_sep>. The values are the
+corresponding, er, values. See L<POSIX/localeconv> for a longer
+example listing the categories an implementation might be expected to
+provide; some provide more and others fewer. You don't need an
+explicit C<use locale>, because localeconv() always observes the
+current locale.
-Here's a simple-minded example program which rewrites its command line
-parameters as integers formatted correctly in the current locale:
+Here's a simple-minded example program that rewrites its command-line
+parameters as integers correctly formatted in the current locale:
# See comments in previous example
require 5.004;
# Apply defaults if values are missing
$thousands_sep = ',' unless $thousands_sep;
- $grouping = 3 unless $grouping;
+
+ # grouping and mon_grouping are packed lists
+ # of small integers (characters) telling the
+ # grouping (thousand_seps and mon_thousand_seps
+ # being the group dividers) of numbers and
+ # monetary quantities. The integers' meanings:
+ # 255 means no more grouping, 0 means repeat
+ # the previous grouping, 1-254 means use that
+ # as the current grouping. Grouping goes from
+ # right to left (low to high digits). In the
+ # below we cheat slightly by never using anything
+ # else than the first grouping (whatever that is).
+ if ($grouping) {
+ @grouping = unpack("C*", $grouping);
+ } else {
+ @grouping = (3);
+ }
# Format command line params for current locale
for (@ARGV) {
$_ = int; # Chop non-integer part
1 while
- s/(\d)(\d{$grouping}($|$thousands_sep))/$1$thousands_sep$2/;
+ s/(\d)(\d{$grouping[0]}($|$thousands_sep))/$1$thousands_sep$2/;
print "$_";
}
print "\n";
+=head2 I18N::Langinfo
+
+Another interface for querying locale-dependent information is the
+I18N::Langinfo::langinfo() function, available at least in UNIX-like
+systems and VMS.
+
+The following example will import the langinfo() function itself and
+three constants to be used as arguments to langinfo(): a constant for
+the abbreviated first day of the week (the numbering starts from
+Sunday = 1) and two more constants for the affirmative and negative
+answers for a yes/no question in the current locale.
+
+ use I18N::Langinfo qw(langinfo ABDAY_1 YESSTR NOSTR);
+
+ my ($abday_1, $yesstr, $nostr) = map { langinfo } qw(ABDAY_1 YESSTR NOSTR);
+
+ print "$abday_1? [$yesstr/$nostr] ";
+
+In other words, in the "C" (or English) locale the above will probably
+print something like:
+
+ Sun? [yes/no]
+
+See L<I18N::Langinfo> for more information.
+
=head1 LOCALE CATEGORIES
-The subsections which follow describe basic locale categories. As well
-as these, there are some combination categories which allow the
-manipulation of more than one basic category at a time. See
-L<"ENVIRONMENT"> for a discussion of these.
+The following subsections describe basic locale categories. Beyond these,
+some combination categories allow manipulation of more than one
+basic category at a time. See L<"ENVIRONMENT"> for a discussion of these.
=head2 Category LC_COLLATE: Collation
-When in the scope of S<C<use locale>>, Perl looks to the C<LC_COLLATE>
-environment variable to determine the application's notions on the
-collation (ordering) of characters. ('b' follows 'a' in Latin
-alphabets, but where do 'E<aacute>' and 'E<aring>' belong?)
+In the scope of S<C<use locale>>, Perl looks to the C<LC_COLLATE>
+environment variable to determine the application's notions on collation
+(ordering) of characters. For example, 'b' follows 'a' in Latin
+alphabets, but where do 'E<aacute>' and 'E<aring>' belong? And while
+'color' follows 'chocolate' in English, what about in Spanish?
+
+The following collations all make sense and you may meet any of them
+if you "use locale".
+
+ A B C D E a b c d e
+ A a B b C c D d E e
+ a A b B c C d D e E
+ a b c d e A B C D E
-Here is a code snippet that will tell you what are the alphanumeric
-characters in the current locale, in the locale order:
+Here is a code snippet to tell what "word"
+characters are in the current locale, in that locale's order:
use locale;
- print +(sort grep /\w/, map { chr() } 0..255), "\n";
+ print +(sort grep /\w/, map { chr } 0..255), "\n";
Compare this with the characters that you see and their order if you
state explicitly that the locale should be ignored:
no locale;
- print +(sort grep /\w/, map { chr() } 0..255), "\n";
+ print +(sort grep /\w/, map { chr } 0..255), "\n";
This machine-native collation (which is what you get unless S<C<use
locale>> has appeared earlier in the same block) must be used for
As noted in L<USING LOCALES>, C<cmp> compares according to the current
collation locale when C<use locale> is in effect, but falls back to a
-byte-by-byte comparison for strings which the locale says are equal. You
+char-by-char comparison for strings that the locale says are equal. You
can use POSIX::strcoll() if you don't want this fall-back:
use POSIX qw(strcoll);
!strcoll("space and case ignored", "SpaceAndCaseIgnored");
$equal_in_locale will be true if the collation locale specifies a
-dictionary-like ordering which ignores space characters completely, and
+dictionary-like ordering that ignores space characters completely and
which folds case.
-If you have a single string which you want to check for "equality in
+If you have a single string that you want to check for "equality in
locale" against several others, you might think you could gain a little
efficiency by using POSIX::strxfrm() in conjunction with C<eq>:
if $xfrm_string eq strxfrm("mixed-case string");
strxfrm() takes a string and maps it into a transformed string for use
-in byte-by-byte comparisons against other transformed strings during
+in char-by-char comparisons against other transformed strings during
collation. "Under the hood", locale-affected Perl comparison operators
-call strxfrm() for both their operands, then do a byte-by-byte
-comparison of the transformed strings. By calling strxfrm() explicitly,
+call strxfrm() for both operands, then do a char-by-char
+comparison of the transformed strings. By calling strxfrm() explicitly
and using a non locale-affected comparison, the example attempts to save
-a couple of transformations. In fact, it doesn't save anything: Perl
+a couple of transformations. But in fact, it doesn't save anything: Perl
magic (see L<perlguts/Magic Variables>) creates the transformed version of a
-string the first time it's needed in a comparison, then keeps it around
+string the first time it's needed in a comparison, then keeps this version around
in case it's needed again. An example rewritten the easy way with
C<cmp> runs just about as fast. It also copes with null characters
embedded in strings; if you call strxfrm() directly, it treats the first
-null it finds as a terminator. And don't expect the transformed strings
-it produces to be portable across systems - or even from one revision
+null it finds as a terminator. don't expect the transformed strings
+it produces to be portable across systems--or even from one revision
of your operating system to the next. In short, don't call strxfrm()
directly: let Perl do it for you.
-Note: C<use locale> isn't shown in some of these examples, as it isn't
+Note: C<use locale> isn't shown in some of these examples because it isn't
needed: strcoll() and strxfrm() exist only to generate locale-dependent
results, and so always obey the current C<LC_COLLATE> locale.
=head2 Category LC_CTYPE: Character Types
-When in the scope of S<C<use locale>>, Perl obeys the C<LC_CTYPE> locale
+In the scope of S<C<use locale>>, Perl obeys the C<LC_CTYPE> locale
setting. This controls the application's notion of which characters are
alphabetic. This affects Perl's C<\w> regular expression metanotation,
-which stands for alphanumeric characters - that is, alphabetic and
-numeric characters. (Consult L<perlre> for more information about
+which stands for alphanumeric characters--that is, alphabetic,
+numeric, and including other special characters such as the underscore or
+hyphen. (Consult L<perlre> for more information about
regular expressions.) Thanks to C<LC_CTYPE>, depending on your locale
setting, characters like 'E<aelig>', 'E<eth>', 'E<szlig>', and
'E<oslash>' may be understood as C<\w> characters.
-The C<LC_CTYPE> locale also provides the map used in translating
+The C<LC_CTYPE> locale also provides the map used in transliterating
characters between lower and uppercase. This affects the case-mapping
-functions - lc(), lcfirst, uc() and ucfirst(); case-mapping
-interpolation with C<\l>, C<\L>, C<\u> or <\U> in double-quoted strings
-and in C<s///> substitutions; and case-independent regular expression
+functions--lc(), lcfirst, uc(), and ucfirst(); case-mapping
+interpolation with C<\l>, C<\L>, C<\u>, or C<\U> in double-quoted strings
+and C<s///> substitutions; and case-independent regular expression
pattern matching using the C<i> modifier.
-Finally, C<LC_CTYPE> affects the POSIX character-class test functions -
-isalpha(), islower() and so on. For example, if you move from the "C"
-locale to a 7-bit Scandinavian one, you may find - possibly to your
-surprise - that "|" moves from the ispunct() class to isalpha().
+Finally, C<LC_CTYPE> affects the POSIX character-class test
+functions--isalpha(), islower(), and so on. For example, if you move
+from the "C" locale to a 7-bit Scandinavian one, you may find--possibly
+to your surprise--that "|" moves from the ispunct() class to isalpha().
B<Note:> A broken or malicious C<LC_CTYPE> locale definition may result
in clearly ineligible characters being considered to be alphanumeric by
-your application. For strict matching of (unaccented) letters and
-digits - for example, in command strings - locale-aware applications
+your application. For strict matching of (mundane) letters and
+digits--for example, in command strings--locale-aware applications
should use C<\w> inside a C<no locale> block. See L<"SECURITY">.
=head2 Category LC_NUMERIC: Numeric Formatting
-When in the scope of S<C<use locale>>, Perl obeys the C<LC_NUMERIC>
-locale information, which controls application's idea of how numbers
-should be formatted for human readability by the printf(), sprintf(),
-and write() functions. String to numeric conversion by the
-POSIX::strtod() function is also affected. In most implementations the
-only effect is to change the character used for the decimal point -
-perhaps from '.' to ',': these functions aren't aware of such niceties
-as thousands separation and so on. (See L<The localeconv function> if
-you care about these things.)
-
-Note that output produced by print() is B<never> affected by the
-current locale: it is independent of whether C<use locale> or C<no
-locale> is in effect, and corresponds to what you'd get from printf()
-in the "C" locale. The same is true for Perl's internal conversions
-between numeric and string formats:
+In the scope of S<C<use locale>>, Perl obeys the C<LC_NUMERIC> locale
+information, which controls an application's idea of how numbers should
+be formatted for human readability by the printf(), sprintf(), and
+write() functions. String-to-numeric conversion by the POSIX::strtod()
+function is also affected. In most implementations the only effect is to
+change the character used for the decimal point--perhaps from '.' to ','.
+These functions aren't aware of such niceties as thousands separation and
+so on. (See L<The localeconv function> if you care about these things.)
+
+Output produced by print() is also affected by the current locale: it
+depends on whether C<use locale> or C<no locale> is in effect, and
+corresponds to what you'd get from printf() in the "C" locale. The
+same is true for Perl's internal conversions between numeric and
+string formats:
use POSIX qw(strtod);
use locale;
$n = 5/2; # Assign numeric 2.5 to $n
- $a = " $n"; # Locale-independent conversion to string
+ $a = " $n"; # Locale-dependent conversion to string
- print "half five is $n\n"; # Locale-independent output
+ print "half five is $n\n"; # Locale-dependent output
printf "half five is %g\n", $n; # Locale-dependent output
print "DECIMAL POINT IS COMMA\n"
if $n == (strtod("2,5"))[0]; # Locale-dependent conversion
+See also L<I18N::Langinfo> and C<RADIXCHAR>.
+
=head2 Category LC_MONETARY: Formatting of monetary amounts
-The C standard defines the C<LC_MONETARY> category, but no function that
-is affected by its contents. (Those with experience of standards
+The C standard defines the C<LC_MONETARY> category, but no function
+that is affected by its contents. (Those with experience of standards
committees will recognize that the working group decided to punt on the
issue.) Consequently, Perl takes no notice of it. If you really want
-to use C<LC_MONETARY>, you can query its contents - see L<The localeconv
-function> - and use the information that it returns in your
-application's own formatting of currency amounts. However, you may well
-find that the information, though voluminous and complex, does not quite
-meet your requirements: currency formatting is a hard nut to crack.
+to use C<LC_MONETARY>, you can query its contents--see
+L<The localeconv function>--and use the information that it returns in your
+application's own formatting of currency amounts. However, you may well
+find that the information, voluminous and complex though it may be, still
+does not quite meet your requirements: currency formatting is a hard nut
+to crack.
+
+See also L<I18N::Langinfo> and C<CRNCYSTR>.
=head2 LC_TIME
-The output produced by POSIX::strftime(), which builds a formatted
+Output produced by POSIX::strftime(), which builds a formatted
human-readable date/time string, is affected by the current C<LC_TIME>
locale. Thus, in a French locale, the output produced by the C<%B>
format element (full month name) for the first month of the year would
-be "janvier". Here's how to get a list of the long month names in the
+be "janvier". Here's how to get a list of long month names in the
current locale:
use POSIX qw(strftime);
strftime("%B", 0, 0, 0, 1, $_, 96);
}
-Note: C<use locale> isn't needed in this example: as a function which
+Note: C<use locale> isn't needed in this example: as a function that
exists only to generate locale-dependent results, strftime() always
obeys the current C<LC_TIME> locale.
+See also L<I18N::Langinfo> and C<ABDAY_1>..C<ABDAY_7>, C<DAY_1>..C<DAY_7>,
+C<ABMON_1>..C<ABMON_12>, and C<ABMON_1>..C<ABMON_12>.
+
=head2 Other categories
-The remaining locale category, C<LC_MESSAGES> (possibly supplemented by
-others in particular implementations) is not currently used by Perl -
-except possibly to affect the behavior of library functions called by
-extensions which are not part of the standard Perl distribution.
+The remaining locale category, C<LC_MESSAGES> (possibly supplemented
+by others in particular implementations) is not currently used by
+Perl--except possibly to affect the behavior of library functions
+called by extensions outside the standard Perl distribution and by the
+operating system and its utilities. Note especially that the string
+value of C<$!> and the error messages given by external utilities may
+be changed by C<LC_MESSAGES>. If you want to have portable error
+codes, use C<%!>. See L<Errno>.
=head1 SECURITY
-While the main discussion of Perl security issues can be found in
+Although the main discussion of Perl security issues can be found in
L<perlsec>, a discussion of Perl's locale handling would be incomplete
if it did not draw your attention to locale-dependent security issues.
-Locales - particularly on systems which allow unprivileged users to
-build their own locales - are untrustworthy. A malicious (or just plain
+Locales--particularly on systems that allow unprivileged users to
+build their own locales--are untrustworthy. A malicious (or just plain
broken) locale can make a locale-aware application give unexpected
results. Here are a few possibilities:
=item *
Regular expression checks for safe file names or mail addresses using
-C<\w> may be spoofed by an C<LC_CTYPE> locale which claims that
+C<\w> may be spoofed by an C<LC_CTYPE> locale that claims that
characters such as "E<gt>" and "|" are alphanumeric.
=item *
=item *
-If the decimal point character in the C<LC_NUMERIC> locale is
-surreptitiously changed from a dot to a comma, C<sprintf("%g",
-0.123456e3)> produces a string result of "123,456". Many people would
-interpret this as one hundred and twenty-three thousand, four hundred
-and fifty-six.
-
-=item *
-
A sneaky C<LC_COLLATE> locale could result in the names of students with
"D" grades appearing ahead of those with "A"s.
=item *
-An application which takes the trouble to use the information in
+An application that takes the trouble to use information in
C<LC_MONETARY> may format debits as if they were credits and vice versa
-if that locale has been subverted. Or it make may make payments in US
+if that locale has been subverted. Or it might make payments in US
dollars instead of Hong Kong dollars.
=item *
The date and day names in dates formatted by strftime() could be
manipulated to advantage by a malicious user able to subvert the
-C<LC_DATE> locale. ("Look - it says I wasn't in the building on
+C<LC_DATE> locale. ("Look--it says I wasn't in the building on
Sunday.")
=back
Such dangers are not peculiar to the locale system: any aspect of an
-application's environment which may maliciously be modified presents
+application's environment which may be modified maliciously presents
similar challenges. Similarly, they are not specific to Perl: any
-programming language which allows you to write programs which take
+programming language that allows you to write programs that take
account of their environment exposes you to these issues.
-Perl cannot protect you from all of the possibilities shown in the
-examples - there is no substitute for your own vigilance - but, when
+Perl cannot protect you from all possibilities shown in the
+examples--there is no substitute for your own vigilance--but, when
C<use locale> is in effect, Perl uses the tainting mechanism (see
-L<perlsec>) to mark string results which become locale-dependent, and
+L<perlsec>) to mark string results that become locale-dependent, and
which may be untrustworthy in consequence. Here is a summary of the
-tainting behavior of operators and functions which may be affected by
+tainting behavior of operators and functions that may be affected by
the locale:
=over 4
-=item B<Comparison operators> (C<lt>, C<le>, C<ge>, C<gt> and C<cmp>):
+=item *
+
+B<Comparison operators> (C<lt>, C<le>, C<ge>, C<gt> and C<cmp>):
Scalar true/false (or less/equal/greater) result is never tainted.
-=item B<Case-mapping interpolation> (with C<\l>, C<\L>, C<\u> or <\U>)
+=item *
+
+B<Case-mapping interpolation> (with C<\l>, C<\L>, C<\u> or C<\U>)
Result string containing interpolated material is tainted if
C<use locale> is in effect.
-=item B<Matching operator> (C<m//>):
+=item *
+
+B<Matching operator> (C<m//>):
Scalar true/false result never tainted.
-Subpatterns, either delivered as an array-context result, or as $1 etc.
+Subpatterns, either delivered as a list-context result or as $1 etc.
are tainted if C<use locale> is in effect, and the subpattern regular
expression contains C<\w> (to match an alphanumeric character), C<\W>
(non-alphanumeric character), C<\s> (white-space character), or C<\S>
-(non white-space character). The matched pattern variable, $&, $`
+(non white-space character). The matched-pattern variable, $&, $`
(pre-match), $' (post-match), and $+ (last match) are also tainted if
C<use locale> is in effect and the regular expression contains C<\w>,
C<\W>, C<\s>, or C<\S>.
-=item B<Substitution operator> (C<s///>):
+=item *
+
+B<Substitution operator> (C<s///>):
Has the same behavior as the match operator. Also, the left
-operand of C<=~> becomes tainted when C<use locale> in effect,
-if it is modified as a result of a substitution based on a regular
+operand of C<=~> becomes tainted when C<use locale> in effect
+if modified as a result of a substitution based on a regular
expression match involving C<\w>, C<\W>, C<\s>, or C<\S>; or of
-case-mapping with C<\l>, C<\L>,C<\u> or <\U>.
+case-mapping with C<\l>, C<\L>,C<\u> or C<\U>.
-=item B<In-memory formatting function> (sprintf()):
+=item *
-Result is tainted if "use locale" is in effect.
+B<Output formatting functions> (printf() and write()):
-=item B<Output formatting functions> (printf() and write()):
+Results are never tainted because otherwise even output from print,
+for example C<print(1/7)>, should be tainted if C<use locale> is in
+effect.
-Success/failure result is never tainted.
+=item *
-=item B<Case-mapping functions> (lc(), lcfirst(), uc(), ucfirst()):
+B<Case-mapping functions> (lc(), lcfirst(), uc(), ucfirst()):
Results are tainted if C<use locale> is in effect.
-=item B<POSIX locale-dependent functions> (localeconv(), strcoll(),
+=item *
+
+B<POSIX locale-dependent functions> (localeconv(), strcoll(),
strftime(), strxfrm()):
Results are never tainted.
-=item B<POSIX character class tests> (isalnum(), isalpha(), isdigit(),
+=item *
+
+B<POSIX character class tests> (isalnum(), isalpha(), isdigit(),
isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(),
isxdigit()):
or warn "Open of $untainted_output_file failed: $!\n";
The program can be made to run by "laundering" the tainted value through
-a regular expression: the second example - which still ignores locale
-information - runs, creating the file named on its command line
+a regular expression: the second example--which still ignores locale
+information--runs, creating the file named on its command line
if it can.
#/usr/local/bin/perl -T
open(F, ">$untainted_output_file")
or warn "Open of $untainted_output_file failed: $!\n";
-Compare this with a very similar program which is locale-aware:
+Compare this with a similar but locale-aware program:
#/usr/local/bin/perl -T
or warn "Open of $localized_output_file failed: $!\n";
This third program fails to run because $& is tainted: it is the result
-of a match involving C<\w> when C<use locale> is in effect.
+of a match involving C<\w> while C<use locale> is in effect.
=head1 ENVIRONMENT
A string that can suppress Perl's warning about failed locale settings
at startup. Failure can occur if the locale support in the operating
-system is lacking (broken) is some way - or if you mistyped the name of
-a locale when you set up your environment. If this environment variable
-is absent, or has a value which does not evaluate to integer zero - that
-is "0" or "" - Perl will complain about locale setting failures.
+system is lacking (broken) in some way--or if you mistyped the name of
+a locale when you set up your environment. If this environment
+variable is absent, or has a value that does not evaluate to integer
+zero--that is, "0" or ""-- Perl will complain about locale setting
+failures.
B<NOTE>: PERL_BADLANG only gives you a way to hide the warning message.
The message tells about some problem in your system's locale support,
=item LC_ALL
-C<LC_ALL> is the "override-all" locale environment variable. If it is
+C<LC_ALL> is the "override-all" locale environment variable. If
set, it overrides all the rest of the locale environment variables.
+=item LANGUAGE
+
+B<NOTE>: C<LANGUAGE> is a GNU extension, it affects you only if you
+are using the GNU libc. This is the case if you are using e.g. Linux.
+If you are using "commercial" UNIXes you are most probably I<not>
+using GNU libc and you can ignore C<LANGUAGE>.
+
+However, in the case you are using C<LANGUAGE>: it affects the
+language of informational, warning, and error messages output by
+commands (in other words, it's like C<LC_MESSAGES>) but it has higher
+priority than L<LC_ALL>. Moreover, it's not a single value but
+instead a "path" (":"-separated list) of I<languages> (not locales).
+See the GNU C<gettext> library documentation for more information.
+
=item LC_CTYPE
In the absence of C<LC_ALL>, C<LC_CTYPE> chooses the character type
=head2 Backward compatibility
Versions of Perl prior to 5.004 B<mostly> ignored locale information,
-generally behaving as if something similar to the C<"C"> locale (see
-L<The setlocale function>) was always in force, even if the program
-environment suggested otherwise. By default, Perl still behaves this
-way so as to maintain backward compatibility. If you want a Perl
-application to pay attention to locale information, you B<must> use
-the S<C<use locale>> pragma (see L<The use locale Pragma>) to
-instruct it to do so.
+generally behaving as if something similar to the C<"C"> locale were
+always in force, even if the program environment suggested otherwise
+(see L<The setlocale function>). By default, Perl still behaves this
+way for backward compatibility. If you want a Perl application to pay
+attention to locale information, you B<must> use the S<C<use locale>>
+pragma (see L<The use locale pragma>) to instruct it to do so.
Versions of Perl from 5.002 to 5.003 did use the C<LC_CTYPE>
-information if that was available, that is, C<\w> did understand what
-are the letters according to the locale environment variables.
+information if available; that is, C<\w> did understand what
+were the letters according to the locale environment variables.
The problem was that the user had no control over the feature:
if the C library supported locales, Perl used them.
=head2 I18N:Collate obsolete
-In versions of Perl prior to 5.004 per-locale collation was possible
+In versions of Perl prior to 5.004, per-locale collation was possible
using the C<I18N::Collate> library module. This module is now mildly
obsolete and should be avoided in new applications. The C<LC_COLLATE>
functionality is now integrated into the Perl core language: One can
=head2 write() and LC_NUMERIC
-Formats are the only part of Perl which unconditionally use information
+Formats are the only part of Perl that unconditionally use information
from a program's locale; if a program's environment specifies an
LC_NUMERIC locale, it is always used to specify the decimal point
character in formatted output. Formatted output cannot be controlled by
=head2 Freely available locale definitions
There is a large collection of locale definitions at
-C<ftp://dkuug.dk/i18n/WG15-collection>. You should be aware that it is
+ftp://dkuug.dk/i18n/WG15-collection . You should be aware that it is
unsupported, and is not claimed to be fit for any purpose. If your
-system allows the installation of arbitrary locales, you may find the
+system allows installation of arbitrary locales, you may find the
definitions useful as they are, or as a basis for the development of
your own locales.
into bankers, bikers, gamers, and so on. But, for now, it's the only
standard we've got. This may be construed as a bug.
+=head1 Unicode and UTF-8
+
+The support of Unicode is new starting from Perl version 5.6, and
+more fully implemented in the version 5.8. See L<perluniintro> and
+L<perlunicode> for more details.
+
+Usually locale settings and Unicode do not affect each other, but
+there are exceptions, see L<perlunicode/Locales> for examples.
+
=head1 BUGS
=head2 Broken systems
-In certain system environments the operating system's locale support
+In certain systems, the operating system's locale support
is broken and cannot be fixed or used by Perl. Such deficiencies can
and will result in mysterious hangs and/or Perl core dumps when the
C<use locale> is in effect. When confronted with such a system,
-please report in excruciating detail to <F<perlbug@perl.com>>, and
-complain to your vendor: maybe some bug fixes exist for these problems
+please report in excruciating detail to <F<perlbug@perl.org>>, and
+complain to your vendor: bug fixes may exist for these problems
in your operating system. Sometimes such bug fixes are called an
operating system upgrade.
=head1 SEE ALSO
-L<POSIX (3)/isalnum>, L<POSIX (3)/isalpha>, L<POSIX (3)/isdigit>,
-L<POSIX (3)/isgraph>, L<POSIX (3)/islower>, L<POSIX (3)/isprint>,
-L<POSIX (3)/ispunct>, L<POSIX (3)/isspace>, L<POSIX (3)/isupper>,
-L<POSIX (3)/isxdigit>, L<POSIX (3)/localeconv>, L<POSIX (3)/setlocale>,
-L<POSIX (3)/strcoll>, L<POSIX (3)/strftime>, L<POSIX (3)/strtod>,
-L<POSIX (3)/strxfrm>
+L<I18N::Langinfo>, L<perluniintro>, L<perlunicode>, L<open>,
+L<POSIX/isalnum>, L<POSIX/isalpha>,
+L<POSIX/isdigit>, L<POSIX/isgraph>, L<POSIX/islower>,
+L<POSIX/isprint>, L<POSIX/ispunct>, L<POSIX/isspace>,
+L<POSIX/isupper>, L<POSIX/isxdigit>, L<POSIX/localeconv>,
+L<POSIX/setlocale>, L<POSIX/strcoll>, L<POSIX/strftime>,
+L<POSIX/strtod>, L<POSIX/strxfrm>.
=head1 HISTORY
Jarkko Hietaniemi's original F<perli18n.pod> heavily hacked by Dominic
-Dunlop, assisted by the perl5-porters.
+Dunlop, assisted by the perl5-porters. Prose worked over a bit by
+Tom Christiansen.
-Last update: Wed Jan 22 11:04:58 EST 1997
+Last update: Thu Jun 11 08:44:13 MDT 1998
https://perl5.git.perl.org / perl5.git / blobdiff