SETLOCALE(3)

NAME
setlocale - natural language formatting for C

LIBRARY
libc

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 isoC-99.

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