9.5 Localization (<locale.h>)

The <locale.h> header file declares two functions and one type and defines several macros.

struct lconv

A structure containing members relating to the formatting of numeric values. The structure contains the following members in any order, with values shown in the comments:

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_MAX  */
char frac_digits;           /*  CHAR_MAX  */
char p_cs_precedes;         /*  CHAR_MAX  */
char p_sep_by_space;        /*  CHAR_MAX  */
char n_cs_precedes;         /*  CHAR_MAX  */
char n_sep_by_space;        /*  CHAR_MAX  */
char p_sign_posn;           /*  CHAR_MAX  */
char n_sign_posn;           /*  CHAR_MAX  */

These members are described under the localeconv function in this section.

Macros

NULL LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME

Expand to integral constant expressions with distinct values, and can be used as the first argument to the setlocale function.

Functions

char *setlocale(int category, const char *locale);

Selects the appropriate portion of the program's locale as specified by the category and locale arguments. This function can be used to change or query the program's entire current locale or portions thereof.

The following values can be specified for the category argument:

LC_ALL-affects the program's entire locale.

LC_COLLATE-affects the behavior of the strcoll and strxfrm functions.

LC_CTYPE-affects the behavior of the character-handling functions and multibyte functions.

LC_MONETARY-affects the monetary-formatting information returned by the localeconv function.

LC_NUMERIC-affects the decimal-point character for the formatted I/O functions and string-conversion functions, as well as the nonmonetary formatting information returned by the localeconv function.

LC_TIME-affects the behavior of the strftime function.

The following values can be specified for the locale argument:

"C"-specifies the minimal environment for C translation
""-specifies the use of the environment variable corresponding to category. If this environment variable is not set, the LANG environment variable is used. If LANG is not set, an error is returned.

At program startup, the equivalent of the following is executed:

setlocale(LC_ALL, "C");

The setlocale function returns one of the following:

If a pointer to a string is specified for locale and the selection can be honored, setlocale returns a pointer to the string associated with the specified category for the new locale. If the selection cannot be honored, setlocale returns a null pointer and the program's locale is not changed.
If a null pointer is specified for locale, setlocale returns a pointer to the string associated with the category for the program's current locale. The program's locale is not changed.

In either case, the returned pointer to the string is such that a subsequent call with that string value and its associated category will restore that part of the program's locale. This string must not be modified by the program, but it can be overwritten by subsequent calls to setlocale .

struct lconv *localeconv(void);

Sets the components of an object with type

struct
   lconv

with values appropriate for formatting numeric quantities according to the rules of the current locale.

The structure members with type char * are pointers to strings, any of which (except decimal_point ) can point to "", which indicates that the value has zero length or is not available in the current locale. Structure members of type char are nonnegative numbers, any of which can be CHAR_MAX to indicate that the value is not available in the current locale. Structure members include the following:

char *decimal_point
The decimal-point character used to format nonmonetary quantities.

char *thousands_sep
The character used to separate groups of digits before the decimal point in formatted nonmonetary quantities.

char *grouping
A string whose elements indicate the size of each group of digits in formatted nonmonetary quantities.

char *int_curr_symbol
The international currency symbol applicable to the current locale. The first three characters contain the alphabetic international currency symbol in accordance with those specified in ISO 4217 Codes for the Representation of Currency and Funds. The fourth character (immediately preceding the null character) is the character used to separate the international currency symbol from the monetary quantity.

char *currency_symbol
The local currency symbol applicable to the current locale.

char *mon_decimal_point
The decimal-point character used to format monetary quantities.

char *mon_thousands_sep
The character used to separate groups of digits before the decimal point in formatted monetary quantities.

char *mon_grouping
A string whose elements indicate the size of each group of digits in formatted monetary quantities.

char *positive_sign
The string used to indicate a nonnegative formatted monetary quantity.

char *negative_sign
The string used to indicate a negative formatted monetary quantity.

char int_frac_digits
The number of fractional digits to be displayed in internationally formatted monetary quantities.

char frac_digits
The number of fractional digits to be displayed in formatted monetary quantities.

char p_cs_precedes
Set to 1 if the currency_symbol precedes the value for a nonnegative formatted monetary quantity; set to 0 if the currency_symbol follows the value.

char p_sep_by_space
Set to 1 if the currency_symbol is separated by a space from the value for a nonnegative formatted monetary quantity; set to 0 if there is no space.

char n_cs_precedes
Set to 1 if the currency_symbol precedes the value for a negative formatted monetary quantity; set to 0 if the currency_symbol follows the value.

char n_sep_by_space
Set to 1 if the currency_symbol is separated by a space from the value for a negative formatted monetary quantity; set to 0 if there is no space.

char p_sign_posn
Set to a value indicating the positioning of the positive_sign for a nonnegative formatted monetary quantity.

char n_sign_posn
Set to a value indicating the positioning of the negative_sign for a negative formatted monetary quantity.

The elements of grouping and mon_ grouping are interpreted according to the following:

CHAR_MAX -no further grouping is to be performed.
0-the previous element is to be repeatedly used for the remainder of the digits.
other-the integer value is the number of digits that comprise the current group. The next element is examined to determine the size of the next group of digits before the current group.

The value of p_sign_posn and n_sign_ posn is interpreted as follows:

0-parentheses surround the quantity and currency_ symbol
1-the sign string precedes the quantity and currency_symbol
2-the sign string follows the quantity and currency_symbol
3-the sign string immediately precedes the currency_symbol
4-the sign string immediately follows the currency_symbol

The localeconv function returns a pointer to the filled in structure. The structure must not be modified by the program, but might be overwritten by subsequent calls to localeconv or to setlocale with categories LC_ALL , LC_MONETARY , or LC_NUMERIC .

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