A locale is a set of language and cultural rules.
These cover aspects
such as language for messages, different character sets, lexicographic
conventions, etc.
A program needs to be able to determine its locale
and act accordingly to be portable to different cultures.
The header
<locale.h>
declares data types, functions and macros which are useful in this
task.
The functions it declares are
setlocale(3)
to set the current locale, and
localeconv(3)
to get information about number formatting.
There are different categories for local information a program might
need; they are declared as macros.
Using them as the first argument
to the
setlocale(3)
function, it is possible to set one of these to the desired locale:
LC_COLLATE
This is used to change the behavior of the functions
strcoll(3)
and
strxfrm(3),
which are used to compare strings in the local alphabet.
For example,
the German sharp s is sorted as "ss".
LC_CTYPE
This changes the behavior of the character handling and
classification functions, such as
isupper(3)
and
toupper(3),
and the multi-byte character functions such as
mblen(3)
or
wctomb(3).
LC_MONETARY
changes the information returned by
localeconv(3)
which describes the way numbers are usually printed, with details such
as decimal point versus decimal comma.
This information is internally
used by the function
strfmon(3).
LC_MESSAGES
changes the language messages are displayed in and what an affirmative or
negative answer looks like.
The GNU C-library contains the
gettext(3),
ngettext(3),
and
rpmatch(3)
functions to ease the use of these information.
The GNU gettext family of
functions also obey the environment variable
LANGUAGE.
LC_NUMERIC
changes the information used by the
printf(3)
and
scanf(3)
family of functions, when they are advised to use the locale-settings.
This information can also be read with the
localeconv(3)
function.
LC_TIME
changes the behavior of the
strftime(3)
function to display the current time in a locally acceptable form; for
example, most of Europe uses a 24-hour clock versus the
12-hour clock used in the United States.
LC_ALL
All of the above.
If the second argument to
setlocale(3)
is empty string,
,
for the default locale, it is determined using the following steps:
1.
If there is a non-null environment variable
LC_ALL,
the value of
LC_ALL
is used.
2.
If an environment variable with the same name as one of the categories
above exists and is non-null, its value is used for that category.
3.
If there is a non-null environment variable
LANG,
the value of
LANG
is used.
Values about local numeric formatting is made available in a
struct lconv
returned by the
localeconv(3)
function, which has the following declaration:
struct lconv {
/* Numeric (non-monetary) information */
char *decimal_point; /* Radix character */
char *thousands_sep; /* Separator for digit groups to left
of radix character */
char *grouping; /* Each element is the number of digits in a
group; elements with higher indices are
further left. An element with value CHAR_MAX
means that no further grouping is done. An
element with value 0 means that the previous
element is used for all groups further left. */
/* Remaining fields are for monetary information */
char *int_curr_symbol; /* First three chars are a currency symbol
from ISO 4217. Fourth char is the
separator. Fifth char is aq\0aq. */
char *currency_symbol; /* Local currency symbol */
char *mon_decimal_point; /* Radix character */
char *mon_thousands_sep; /* Like thousands_sep above */
char *mon_grouping; /* Like grouping above */
char *positive_sign; /* Sign for positive values */
char *negative_sign; /* Sign for negative values */
char int_frac_digits; /* International fractional digits */
char frac_digits; /* Local fractional digits */
char p_cs_precedes; /* 1 if currency_symbol precedes a
positive value, 0 if succeeds */
char p_sep_by_space; /* 1 if a space separates currency_symbol
from a positive value */
char n_cs_precedes; /* 1 if currency_symbol precedes a
negative value, 0 if succeeds */
char n_sep_by_space; /* 1 if a space separates currency_symbol
from a negative value */
/* Positive and negative sign positions:
0 Parentheses surround the quantity and currency_symbol.
1 The sign string precedes the quantity and currency_symbol.
2 The sign string succeeds the quantity and currency_symbol.
3 The sign string immediately precedes the currency_symbol.
4 The sign string immediately succeeds the currency_symbol. */
char p_sign_posn;
char n_sign_posn;
};
CONFORMING TO
POSIX.1-2001.
The GNU gettext functions are specified in LI18NUX2000.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.