NAME
setlocale
,
localeconv
—
natural language formatting for
C
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(3) and strxfrm(3).
LC_CTYPE
- Set a locale for the functions declared in
<ctype.h>
and<wctype.h>
. This controls recognition of upper and lower case, alphabetic or non-alphabetic characters, and so on. LC_MESSAGES
- Set a locale for message strings. Controls the behaviour of catopen(3) and internationalization tools.
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(3) and
scanf(3), as well as values returned by
localeconv
(). LC_TIME
- Set a locale for formatting dates and times using the strftime(3) 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 only function in the library that sets the locale
is setlocale
(); the locale is never changed as a
side effect of some other routine.
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_p_sep_by_space; char int_n_cs_precedes; 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 currency values.
- thousands_sep
- The separator between groups of digits before the decimal point, except for currency values.
- grouping
- The sizes of the groups of digits, except for currency 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 orCHAR_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 withCHAR_MAX
, no more grouping is performed. - int_curr_symbol
- The standardized international currency symbol.
- currency_symbol
- The local currency symbol.
- mon_decimal_point
- The decimal point character for currency values.
- mon_thousands_sep
- The separator for digit groups in currency values.
- mon_grouping
- Like grouping but for currency values.
- positive_sign
- The character used to denote non-negative currency values, usually the empty string.
- negative_sign
- The character used to denote negative currency values, usually a minus sign.
- int_frac_digits
- The number of digits after the decimal point in an international-style currency value.
- frac_digits
- The number of digits after the decimal point in the local style for currency values.
- p_cs_precedes
- 1 if the currency symbol precedes the currency value for non-negative values, 0 if it follows.
- p_sep_by_space
- 1 if a space is inserted between the currency symbol and the currency value for non-negative 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
non-negative quantity and the currency_symbol, coded
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.
- n_sign_posn
- Like p_sign_posn but for negative currency values.
- int_p_cs_precedes
- Like p_cs_precedes but for the international symbol.
- int_n_cs_precedes
- Like n_cs_precedes but for the international symbol.
- int_p_sep_by_space
- Like p_sep_by_space but for the international symbol.
- int_n_sep_by_space
- Like n_sep_by_space but for the international symbol.
- int_p_sign_posn
- Like p_sign_posn but for the international symbol.
- int_n_sign_posn
- Like n_sign_posn but for the international 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
().
SEE ALSO
mklocale(1), catopen(3), printf(3), scanf(3), strcoll(3), strftime(3), strxfrm(3)
STANDARDS
The setlocale
() and
localeconv
() functions conform to
ANSI X3.159-1989
(“ANSI C89”).
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 conversion function.
LC_NUMERIC
and LC_TIME
are
personal choices and should not be wrapped up with the other categories.