SETLOCALE(3) BSD Library Functions Manual SETLOCALE(3)NAME
setlocale, localeconv — natural language formatting for C
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <locale.h>
char *
setlocale(int category, const char *locale);
struct lconv *
localeconv(void);
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 localeconv() routine returns the current locale's parameters
for formatting numbers.
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) functions. This controls
recognition of upper and lower case, alphabetic or non-
alphabetic characters, and so on. The real work is done by
the setrunelocale() function.
LC_MESSAGES Set a locale for message catalogs. This controls the selec‐
tion of message catalogs by the catgets(3) and gettext(3)
families of functions.
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 for‐
matting 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.
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. By default, C programs start
in the "C" locale. The format of the locale string is described in
nls(7).
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.
Changing the setting of LC_MESSAGES has no effect on catalogs that have
already been opened by catopen(3).
The localeconv() function returns a pointer to a structure which provides
parameters for formatting numbers, especially currency values:
struct lconv {
char *decimal_point;
char *thousands_sep;
char *grouping;
char *int_curr_symbol;
char *currency_symbol;
char *mon_decimal_point;
char *mon_thousands_sep;
char *mon_grouping;
char *positive_sign;
char *negative_sign;
char int_frac_digits;
char frac_digits;
char p_cs_precedes;
char p_sep_by_space;
char n_cs_precedes;
char n_sep_by_space;
char p_sign_posn;
char n_sign_posn;
char int_p_cs_precedes;
char int_n_cs_precedes;
char int_p_sep_by_space;
char int_n_sep_by_space;
char int_p_sign_posn;
char int_n_sign_posn;
};
The individual fields have the following meanings:
decimal_point The decimal point character, except for monetary val‐
ues.
thousands_sep The separator between groups of digits before the
decimal point, except for monetary values.
grouping The sizes of the groups of digits, except for mone‐
tary values. This is a pointer to a vector of inte‐
gers, each of size char, representing group size from
low order digit groups to high order (right to left).
The list may be terminated with 0 or CHAR_MAX. If
the list is terminated with 0, the last group size
before the 0 is repeated to account for all the dig‐
its. If the list is terminated with CHAR_MAX, no
more grouping is performed.
int_curr_symbol The standardized (ISO 4217:1995) international cur‐
rency symbol.
currency_symbol The local currency symbol.
mon_decimal_point The decimal point character for monetary values.
mon_thousands_sep The separator for digit groups in monetary values.
mon_grouping Like grouping but for monetary values.
positive_sign The character used to denote nonnegative monetary
values, usually the empty string.
negative_sign The character used to denote negative monetary val‐
ues, usually a minus sign.
int_frac_digits The number of digits after the decimal point in an
internationally formatted monetary value.
frac_digits The number of digits after the decimal point in an
locally formatted monetary value.
p_cs_precedes 1 if the currency symbol precedes the monetary value
for nonnegative values, 0 if it follows.
p_sep_by_space 1 if a space is inserted between the currency symbol
and the monetary value for nonnegative values, 0 oth‐
erwise.
n_cs_precedes Like p_cs_precedes but for negative values.
n_sep_by_space Like p_sep_by_space but for negative values.
p_sign_posn The location of the positive_sign with respect to a
nonnegative quantity and the currency_symbol.
n_sign_posn Like p_sign_posn but for negative currency values.
int_p_cs_precedes 1 if the currency symbol precedes the internationally
formatted monetary value for nonnegative values, 0 if
it follows.
int_n_cs_precedes Like int_p_cs_precedes but for negative values.
int_p_sep_by_space 1 if a space is inserted between the currency symbol
and the internationally formatted monetary value for
nonnegative values, 0 otherwise.
int_n_sep_by_space Like int_p_sep_by_space but for negative values.
int_p_sign_posn The location of the positive_sign with respect to a
nonnegative quantity and the currency_symbol, for
internationally formatted nonnegative monetary val‐
ues.
int_n_sign_posn Like int_p_sign_posn but for negative values.
The positional parameters in p_sign_posn, n_sign_posn, int_p_sign_posn
and int_n_sign_posn are encoded as follows:
0 Parentheses around the entire string.
1 Before the string.
2 After the string.
3 Just before currency_symbol.
4 Just after currency_symbol.
Unless mentioned above, an empty string as a value for a field indicates
a zero length result or a value that is not in the current locale. A
CHAR_MAX result similarly denotes an unavailable value.
RETURN VALUES
The setlocale() function returns NULL and fails to change the locale if
the given combination of category and locale makes no sense. The
localeconv() function returns a pointer to a static object which may be
altered by later calls to setlocale() or localeconv().
EXAMPLES
The following code illustrates how a program can initialize the interna‐
tional environment for one language, while selectively modifying the pro‐
gram'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, "");
SEE ALSOcatopen(3), gettext(3), nl_langinfo(3), nls(7)STANDARDS
The setlocale() and localeconv() functions conform to ANSI X3.159-1989
(“ANSI C89”) and ISO/IEC 9899:1990 (“ISO C90”).
The int_p_cs_precedes, int_n_cs_precedes, int_p_sep_by_space,
int_n_sep_by_space, int_p_sign_posn and int_n_sign_posn members of struct
lconv were introduced in ISO/IEC 9899:1999 (“ISO C99”).
HISTORY
The setlocale() and localeconv() functions first appeared in 4.4BSD.
BUGS
The current implementation supports only the "C" and "POSIX" locales for
all but the LC_CTYPE locale.
In spite of the gnarly currency support in localeconv(), the standards
don't include any functions for generalized currency formatting.
LC_COLLATE does not make sense for many languages. Use of LC_MONETARY
could lead to misleading results until we have a real time currency con‐
version function. LC_NUMERIC and LC_TIME are personal choices and should
not be wrapped up with the other categories.
Multibyte locales aren't supported for static binaries.
BSD May 30, 2003 BSD
