NAME

setlocale − modify and query a program’s locale

SYNOPSIS

#include <locale.h>

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

DESCRIPTION

setlocale selects the appropriate piece of the program’s locale as specified by the category and locale arguments.  The category argument may have the following values: LC_CTYPE, LC_NUMERIC, LC_TIME, LC_COLLATE, LC_MONETARY, LC_MESSAGES and LC_ALL. These names are defined in the locale.h header file.  LC_CTYPE affects the behavior of the character handling functions (isdigit, tolower, etc.) and the multibyte character functions (such as mbtowc and wctomb).  LC_NUMERIC affects the decimal-point character for the formatted input/output functions and the string conversion functions as well as the non-monetary formatting information returned by localeconv.  [See localeconv(3C).] LC_TIME affects the behavior of ascftime, cftime, getdate and strftime.  LC_COLLATE affects the behavior of strcoll and strxfrm.  LC_MONETARY affects the monetary formatted information returned by localeconv.  LC_MESSAGES affects the behavior of gettxt, catopen, catclose, and catgets.  [See catopen(3C) and catgets(3C).] LC_ALL names the program’s entire locale. 

Each category corresponds to a set of databases which contain the relevant information for each defined locale.  The location of a database is given by the following path, /usr/lib/locale/locale/category, where locale and category are the names of locale and category, respectively.  For example, the database for the LC_CTYPE category for the "german" locale would be found in /usr/lib/locale/german/LC_CTYPE. 

A value of "C" for locale specifies the default environment. 

A value of "" for locale specifies that the locale should be taken from environment variables.  The order in which the environment variables are checked for the various categories is given below:

At program startup, the equivalent of

setlocale(LC_ALL, "C")

is executed.  This has the effect of initializing each category to the locale described by the environment "C". 

If a pointer to a string is given for locale, setlocale attempts to set the locale for the given category to locale.  If ­setlocale succeeds, locale is returned.  If setlocale fails, a null pointer is returned and the program’s locale is not changed. 

For category LC_ALL, the behavior is slightly different.  If a pointer to a string is given for locale and LC_ALL is given for category, setlocale attempts to set the locale for all the categories to locale.  The locale may be a simple locale, consisting of a single locale, or a composite locale.  A composite locale is a string beginning with a "/" followed by the locale of each category separated by a "/".  If ­setlocale fails to set the locale for any category, a null pointer is returnedand the program’s locale for all categories is not changed.  Otherwise, locale is returned. 

A null pointer for locale causes setlocale to return the current locale associated with the category.  The program’s locale is not changed. 

FILES

/usr/lib/locale/C/LC_CTYPE − LC_CTYPE database for the C locale. 
/usr/lib/locale/C/LC_NUMERIC − LC_NUMERIC database for the C locale. 
/usr/lib/locale/C/LC_TIME − LC_TIME database for the C locale. 
/usr/lib/locale/C/LC_COLLATE − LC_COLLATE database for the C locale. 
/usr/lib/locale/C/LC_MESSAGES − LC_MESSAGES database for the C locale. 
/usr/lib/locale/locale/category − files containing the locale specific information for each locale and category. 

SEE ALSO

ctime(3C), ctype(3C), getdate(3C), gettxt(3G), localeconv(3C), mbtowc(3C), printf(3S), strcoll(3C), strftime(3C), strtod(3C), strxfrm(3C), wctomb(3C), environ(5)

  —  C Programming Language Utilities