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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | HISTORY | NOTES | EXAMPLES | SEE ALSO | COLOPHON |
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nl_langinfo(3) Library Functions Manual nl_langinfo(3)
nl_langinfo, nl_langinfo_l - query language and locale information
Standard C library (libc, -lc)
#include <langinfo.h>
char *nl_langinfo(nl_item item);
char *nl_langinfo_l(nl_item item, locale_t locale);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
nl_langinfo_l():
Since glibc 2.24:
_POSIX_C_SOURCE >= 200809L
glibc 2.23 and earlier:
_POSIX_C_SOURCE >= 200112L
The nl_langinfo() and nl_langinfo_l() functions provide access to
locale information in a more flexible way than localeconv(3).
nl_langinfo() returns a string which is the value corresponding to
item in the program's current global locale. nl_langinfo_l()
returns a string which is the value corresponding to item for the
locale identified by the locale object locale, which was
previously created by newlocale(3). Individual and additional
elements of the locale categories can be queried.
Examples for the locale elements that can be specified in item
using the constants defined in <langinfo.h> are:
CODESET (LC_CTYPE)
Return a string with the name of the character encoding
used in the selected locale, such as "UTF-8", "ISO-8859-1",
or "ANSI_X3.4-1968" (better known as US-ASCII). This is
the same string that you get with "locale charmap". For a
list of character encoding names, try "locale -m" (see
locale(1)).
D_T_FMT (LC_TIME)
Return a string that can be used as a format string for
strftime(3) to represent time and date in a locale-specific
way (%c conversion specification).
D_FMT (LC_TIME)
Return a string that can be used as a format string for
strftime(3) to represent a date in a locale-specific way
(%x conversion specification).
T_FMT (LC_TIME)
Return a string that can be used as a format string for
strftime(3) to represent a time in a locale-specific way
(%X conversion specification).
AM_STR (LC_TIME)
Return a string that represents affix for ante meridiem
(before noon, "AM") time. (Used in %p strftime(3)
conversion specification.)
PM_STR (LC_TIME)
Return a string that represents affix for post meridiem
(before midnight, "PM") time. (Used in %p strftime(3)
conversion specification.)
T_FMT_AMPM (LC_TIME)
Return a string that can be used as a format string for
strftime(3) to represent a time in a.m. or p.m. notation in
a locale-specific way (%r conversion specification).
ERA (LC_TIME)
Return era description, which contains information about
how years are counted and displayed for each era in a
locale. Each era description segment shall have the
format:
direction:offset:start_date:end_date:era_name:era_format
according to the definitions below:
direction
Either a "+" or a "-" character. The "+" means that
years increase from the start_date towards the
end_date, "-" means the opposite.
offset The epoch year of the start_date.
start_date
A date in the form yyyy/mm/dd, where yyyy, mm, and
dd are the year, month, and day numbers respectively
of the start of the era.
end_date
The ending date of the era, in the same format as
the start_date, or one of the two special values
"-*" (minus infinity) or "+*" (plus infinity).
era_name
The name of the era, corresponding to the %EC
strftime(3) conversion specification.
era_format
The format of the year in the era, corresponding to
the %EY strftime(3) conversion specification.
Era description segments are separated by semicolons. Most
locales do not define this value. Examples of locales that
do define this value are the Japanese and Thai locales.
ERA_D_T_FMT (LC_TIME)
Return a string that can be used as a format string for
strftime(3) for alternative representation of time and date
in a locale-specific way (%Ec conversion specification).
ERA_D_FMT (LC_TIME)
Return a string that can be used as a format string for
strftime(3) for alternative representation of a date in a
locale-specific way (%Ex conversion specification).
ERA_T_FMT (LC_TIME)
Return a string that can be used as a format string for
strftime(3) for alternative representation of a time in a
locale-specific way (%EX conversion specification).
DAY_{1–7} (LC_TIME)
Return name of the n-th day of the week. [Warning: this
follows the US convention DAY_1 = Sunday, not the
international convention (ISO 8601) that Monday is the
first day of the week.] (Used in %A strftime(3) conversion
specification.)
ABDAY_{1–7} (LC_TIME)
Return abbreviated name of the n-th day of the week. (Used
in %a strftime(3) conversion specification.)
MON_{1–12} (LC_TIME)
Return name of the n-th month. (Used in %B strftime(3)
conversion specification.)
ABMON_{1–12} (LC_TIME)
Return abbreviated name of the n-th month. (Used in %b
strftime(3) conversion specification.)
RADIXCHAR (LC_NUMERIC)
Return radix character (decimal dot, decimal comma, etc.).
THOUSEP (LC_NUMERIC)
Return separator character for thousands (groups of three
digits).
YESEXPR (LC_MESSAGES)
Return a regular expression that can be used with the
regex(3) function to recognize a positive response to a
yes/no question.
NOEXPR (LC_MESSAGES)
Return a regular expression that can be used with the
regex(3) function to recognize a negative response to a
yes/no question.
CRNCYSTR (LC_MONETARY)
Return the currency symbol, preceded by "-" if the symbol
should appear before the value, "+" if the symbol should
appear after the value, or "." if the symbol should replace
the radix character.
The above list covers just some examples of items that can be
requested. For a more detailed list, consult The GNU C Library
Reference Manual.
On success, these functions return a pointer to a string which is
the value corresponding to item in the specified locale.
If no locale has been selected by setlocale(3) for the appropriate
category, nl_langinfo() return a pointer to the corresponding
string in the "C" locale. The same is true of nl_langinfo_l() if
locale specifies a locale where langinfo data is not defined.
If item is not valid, a pointer to an empty string is returned.
The pointer returned by these functions may point to static data
that may be overwritten, or the pointer itself may be invalidated,
by a subsequent call to nl_langinfo(), nl_langinfo_l(), or
setlocale(3). The same statements apply to nl_langinfo_l() if the
locale object referred to by locale is freed or modified by
freelocale(3) or newlocale(3).
POSIX specifies that the application may not modify the string
returned by these functions.
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────────────────────┬───────────────┬────────────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────┼───────────────┼────────────────┤
│ nl_langinfo() │ Thread safety │ MT-Safe locale │
└───────────────────────────────┴───────────────┴────────────────┘
POSIX.1-2008.
POSIX.1-2001, SUSv2.
The behavior of nl_langinfo_l() is undefined if locale is the
special locale object LC_GLOBAL_LOCALE or is not a valid locale
object handle.
The following program sets the character type and the numeric
locale according to the environment and queries the terminal
character set and the radix character.
#include <langinfo.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
int
main(void)
{
setlocale(LC_CTYPE, "");
setlocale(LC_NUMERIC, "");
printf("%s\n", nl_langinfo(CODESET));
printf("%s\n", nl_langinfo(RADIXCHAR));
exit(EXIT_SUCCESS);
}
locale(1), localeconv(3), setlocale(3), charsets(7), locale(7)
The GNU C Library Reference Manual
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
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improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 nl_langinfo(3)
Pages that refer to this page: find(1), iconv(1), bind_textdomain_codeset(3), localeconv(3), rpmatch(3), setlocale(3), strftime(3), locale(7), utf-8(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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