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.TH SETLOCALE 3  2017-09-15 "GNU" "Linux Programmer's Manual"

.SH NAME

setlocale \- set the current locale

.SH SYNOPSIS

.nf

.B #include <locale.h>

.PP

.BI "char *setlocale(int " category ", const char *" locale );

.fi

.SH DESCRIPTION

The

.BR setlocale ()

function is used to set or query the program's current locale.

.PP

If

.I locale

is not NULL,

the program's current locale is modified according to the arguments.

The argument

.I category

determines which parts of the program's current locale should be modified.

.TS

lB lB

lB l.

Category	Governs

LC_ALL	All of the locale

LC_ADDRESS	T{

Formatting of addresses and

.br

geography-related items (*)

T}

LC_COLLATE	String collation

LC_CTYPE	Character classification

LC_IDENTIFICATION	Metadata describing the locale (*)

LC_MEASUREMENT	T{

Settings related to measurements

.br

(metric versus US customary) (*)

T}

LC_MESSAGES	Localizable natural-language messages

LC_MONETARY	Formatting of monetary values

LC_NAME	Formatting of salutations for persons (*)

LC_NUMERIC	Formatting of nonmonetary numeric values

LC_PAPER	Settings related to the standard paper size (*)

LC_TELEPHONE	Formats to be used with telephone services (*)

LC_TIME	Formatting of date and time values

.TE

.PP

The categories marked with an asterisk in the above table

are GNU extensions.

For further information on these locale categories, see

.BR locale (7).

.PP

The argument

.I locale

is a pointer to a character string containing the

required setting of

.IR category .

Such a string is either a well-known constant like "C" or "da_DK"

(see below), or an opaque string that was returned by another call of

.BR setlocale ().

.PP

If

.I locale

is an empty string,

.BR """""" ,

each part of the locale that should be modified is set according to the

environment variables.

The details are implementation-dependent.

For glibc, first (regardless of

.IR category ),

the environment variable

.B LC_ALL

is inspected,

next the environment variable with the same name as the category

(see the table above),

and finally the environment variable

.BR LANG .

The first existing environment variable is used.

If its value is not a valid locale specification, the locale

is unchanged, and

.BR setlocale ()

returns NULL.

.PP

The locale

.B """C"""

or

.B """POSIX"""

is a portable locale;

it exists on all conforming systems.

.PP

A locale name is typically of the form

.IR language "[_" territory "][." codeset "][@" modifier "],"

where

.I language

is an ISO 639 language code,

.I territory

is an ISO 3166 country code, and

.I codeset

is a character set or encoding identifier like

.B "ISO-8859-1"

or

.BR "UTF-8" .

For a list of all supported locales, try "locale \-a" (see

.BR locale (1)).

.PP

If

.I locale

is NULL, the current locale is only queried, not modified.

.PP

On startup of the main program, the portable

.B """C"""

locale is selected as default.

A program may be made portable to all locales by calling:

.PP

.in +4n

.EX

setlocale(LC_ALL, "");

.EE

.in

.PP

after program initialization, by using the values returned

from a

.BR localeconv (3)

call

for locale-dependent information, by using the multibyte and wide

character functions for text processing if

.BR "MB_CUR_MAX > 1" ,

and by using

.BR strcoll (3),

.BR wcscoll (3)

or

.BR strxfrm (3),

.BR wcsxfrm (3)

to compare strings.

.SH RETURN VALUE

A successful call to

.BR setlocale ()

returns an opaque string that corresponds to the locale set.

This string may be allocated in static storage.

The string returned is such that a subsequent call with that string

and its associated category will restore that part of the process's

locale.

The return value is NULL if the request cannot be honored.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lb lb lbw26

l l l.

Interface	Attribute	Value

T{

.BR setlocale ()

T}	Thread safety	MT-Unsafe const:locale env

.TE

.sp 1

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C89, C99.

.PP

The C standards specify only the categories

.BR LC_ALL ,

.BR LC_COLLATE ,

.BR LC_CTYPE ,

.BR LC_MONETARY ,

.BR LC_NUMERIC ,

and

.BR LC_TIME .

POSIX.1 adds

.BR LC_MESSAGES .

The remaining categories are GNU extensions.

.SH SEE ALSO

.BR locale (1),

.BR localedef (1),

.BR isalpha (3),

.BR localeconv (3),

.BR nl_langinfo (3),

.BR rpmatch (3),

.BR strcoll (3),

.BR strftime (3),

.BR charsets (7),

.BR locale (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.