SETLOCALE(3)           FreeBSD Library Functions Manual           SETLOCALE(3)

NAME
     setlocale - natural language formatting for C

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <locale.h>

     char *
     setlocale(int category, const char *locale);

DESCRIPTION
     The setlocale() function sets the C library's notion of natural language
     formatting style for particular sets of routines.  Each such style is
     called a `locale' and is invoked using an appropriate name passed as a C
     string.

     The setlocale() function recognizes several categories of routines.
     These are the categories and the sets of routines they select:

     LC_ALL       Set the entire locale generically.

     LC_COLLATE   Set a locale for string collation routines.  This controls
                  alphabetic ordering in strcoll() and strxfrm().

     LC_CTYPE     Set a locale for the ctype(3) and multibyte(3) functions.
                  This controls recognition of upper and lower case,
                  alphabetic or non-alphabetic characters, and so on.

     LC_MESSAGES  Set a locale for message catalogs, see catopen(3) function.

     LC_MONETARY  Set a locale for formatting monetary values; this affects
                  the localeconv() function.

     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 printf() and scanf(), as
                  well as values returned by localeconv().

     LC_TIME      Set a locale for formatting dates and times using the
                  strftime() function.

     LANG         Sets the generic locale category for native language, local
                  customs and coded character set in the absence of more
                  specific locale variables.

     Only three locales are defined by default, the empty string "" which
     denotes the native environment, and the "C" and "POSIX" locales, which
     denote the C language environment.  A locale argument of NULL causes
     setlocale() to return the current locale.

     The option -a to the locale(1) command can be used to display all further
     possible names for the locale argument that are recognized.  Specifying
     any unrecognized value for locale makes setlocale() fail.

     By default, C programs start in the "C" locale.

     The only function in the library that sets the locale is setlocale(); the
     locale is never changed as a side effect of some other routine.

RETURN VALUES
     Upon successful completion, setlocale() returns the string associated
     with the specified category for the requested locale.  The setlocale()
     function returns NULL and fails to change the locale if the given
     combination of category and locale makes no sense.

FILES
     $PATH_LOCALE/locale/category
     /usr/share/locale/locale/category  locale file for the locale locale and
                                        the category category.

EXAMPLES
     The following code illustrates how a program can initialize the
     international environment for one language, while selectively modifying
     the program's locale such that regular expressions and string operations
     can be applied to text recorded in a different language:

         setlocale(LC_ALL, "de");
         setlocale(LC_COLLATE, "fr");

     When a process is started, its current locale is set to the C or POSIX
     locale.  An internationalized program that depends on locale data not
     defined in the C or POSIX locale must invoke the setlocale subroutine in
     the following manner before using any of the locale-specific information:

         setlocale(LC_ALL, "");

ERRORS
     No errors are defined.

SEE ALSO
     locale(1), localedef(1), catopen(3), ctype(3), localeconv(3),
     multibyte(3), strcoll(3), strxfrm(3), euc(5), utf8(5), environ(7)

STANDARDS
     The setlocale() function conforms to ISO/IEC 9899:1999 ("ISO C99").

HISTORY
     The setlocale() function first appeared in 4.4BSD.

FreeBSD 13.1-RELEASE-p6         August 7, 2020         FreeBSD 13.1-RELEASE-p6