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.\"	@(#)setlocale.3	8.1 (Berkeley) 6/9/93
.\" $FreeBSD$
.\"
.Dd November 21, 2003
.Dt SETLOCALE 3
.Os
.Sh NAME
.Nm setlocale
.Nd natural language formatting for C
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In locale.h
.Ft char *
.Fo setlocale
.Fa "int category"
.Fa "const char *locale"
.Fc
.Sh DESCRIPTION
The
.Fn setlocale
function sets the C library's notion
of natural language formatting style
for particular sets of routines.
Each such style is called a
.Sq locale
and is invoked using an appropriate name passed as a C string.
.Pp
The
.Fn setlocale
function recognizes several categories of routines.
These are the categories and the sets of routines they select:
.Bl -tag -width LC_MONETARY
.It Dv LC_ALL
Set the entire locale generically.
.It Dv LC_COLLATE
Set a locale for string collation routines.
This controls alphabetic ordering in
.Fn strcoll
and
.Fn strxfrm .
.It Dv LC_CTYPE
Set a locale for the
.Xr ctype 3
and
.Xr multibyte 3
functions.
This controls recognition of upper and lower case,
alphabetic or non-alphabetic characters,
and so on.
.It Dv LC_MESSAGES
Set a locale for message catalogs, see
.Xr catopen 3
function.
.It Dv LC_MONETARY
Set a locale for formatting monetary values;
this affects the
.Fn localeconv
function.
.It Dv LC_NUMERIC
Set a locale for formatting numbers.
This controls the formatting of decimal points
in input and output of floating point numbers
in functions such as
.Fn printf
and
.Fn scanf ,
as well as values returned by
.Fn localeconv .
.It Dv LC_TIME
Set a locale for formatting dates and times using the
.Fn strftime
function.
.El
.Pp
Only three locales are defined by default:
the empty string
.Li \&"\|"
(which denotes the native environment) and the
.Li \&"C"
and
.Li \&"POSIX"
locales (which denote the C language environment).
A
.Fa locale
argument of
.Dv NULL
causes
.Fn setlocale
to return the current locale.  An argument of
.Li \&"\|"
will determine the name of the new locale taking into account the environment
variables LANG and LC_*.  If these environment variables yield a locale that is
invalid, NULL will be returned and the current locale will remain unchanged.
By default, C programs start in the
.Li \&"C"
locale.
The only function in the library that sets the locale is
.Fn setlocale ;
the locale is never changed as a side effect of some other routine.
.Sh RETURN VALUES
Upon successful completion,
.Fn setlocale
returns the string associated with the specified
.Fa category
for the requested
.Fa locale .
The
.Fn setlocale
function returns
.Dv NULL
and fails to change the locale
if the given combination of
.Fa category
and
.Fa locale
makes no sense.
.Sh FILES
.Bl -tag -width /usr/share/locale/locale/category -compact
.It Pa $PATH_LOCALE/ Ns Em locale/category
.It Pa /usr/share/locale/ Ns Em locale/category
locale file for the locale
.Em locale
and the category
.Em category .
.It Pa /usr/local/share/locale/ Ns Em locale/category
locale file for the locale
.Em locale
and the category
.Em category .
.El
.Sh ERRORS
No errors are defined.
.Sh SEE ALSO
.Xr colldef 1 ,
.Xr mklocale 1 ,
.Xr catopen 3 ,
.Xr ctype 3 ,
.Xr localeconv 3 ,
.Xr multibyte 3 ,
.Xr strcoll 3 ,
.Xr strxfrm 3 ,
.Xr euc 5 ,
.Xr utf8 5 ,
.Xr environ 7
.Sh STANDARDS
The
.Fn setlocale
function conforms to
.St -isoC-99 .
.Sh HISTORY
The
.Fn setlocale
function first appeared in
.Bx 4.4 .