SETLOCALE(3) BSD Programmer's Manual SETLOCALE(3)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 recognises 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.
In the current implementation, one additional locale is sup-
ported in this category, namely en_US.UTF-8, which is
selected if the locale string matches "UTF-8" or "utf8",
case-insensitively.
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 set-
locale() 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;
};
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 de-
cimal 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 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 per-
formed.
int_curr_symbol The standardised 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 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
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.
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 lo-
caleconv() function returns a pointer to a static object which may be al-
tered by later calls to setlocale() or localeconv().
STANDARDS
The setlocale() and localeconv() functions conform to ANSI X3.159-1989
("ANSI C").
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, and only the "en_US.UTF-8" LC_CTYPE locale.
In spite of the gnarly currency support in localeconv(), the standards
don't include any functions for generalised 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.
MirOS BSD #10-current November 21, 2006 2
