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.
-
-
LC_MESSAGES
- Set a locale for message catalogs. This controls the
selection 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
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.
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
values.
-
-
- 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 monetary
values. This is a pointer to a vector of integers, 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 digits. If
the list is terminated with CHAR_MAX
, no more
grouping is performed.
-
-
- int_curr_symbol
- The standardized (ISO 4217:1995) international currency
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 values,
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 otherwise.
-
-
- 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 values.
-
-
- 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().
Currently,
setlocale() returns
NULL
and fails to change the locale when
LC_COLLATE
is
modified independently of other values.
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_NUMERIC, "C");
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:
FILES
The use of multibyte locales requires shared libraries located in
/usr/lib/i18n.
SEE ALSO
catopen(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
In spite of the gnarly currency support in
localeconv(), the
standards don't include any functions for generalized currency formatting.
LC_COLLATE
is unimplemented (but does not make sense for
many languages). Use of
LC_MONETARY
could lead to
misleading results until we have a real time currency conversion 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.