![[Go to CFHT Home Page]](/images/cfht-icon.gif){kind=icon}
Man Pages 
Back to Software Index 
Manpage Top Level
#include <locale.h>
char *setlocale(int category, const char *locale);
Safe with exceptions
LC_CTYPE affects the behavior of character handling functions such as isdigit() and tolower(), and multibyte character functions such as mbtowc() and wctomb().
LC_NUMERIC affects the decimal point character and thousands separator character for the formatted input/output functions and string conversion functions.
LC_TIME affects the date and time format as delivered by ascftime(), cftime(), getdate(), and strftime().
LC_COLLATE affects the sort order produced by strcoll() and strxfrm().
LC_MONETARY affects the monetary formatted information returned by localeconv().
LC_MESSAGES affects the behavior of dgettext(), gettext(), and gettxt().
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 of the de (Deutsch or German) locale would be found in /usr/lib/locale/de/LC_CTYPE
A value of "C" for locale specifies the traditional UNIX system behavior. 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".
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:
Category 1st Env. Var. 2nd Env. Var. 3rd Env. Var LC_CTYPE: LC_ALL LC_CTYPE LANG LC_COLLATE: LC_ALL LC_COLLATE LANG LC_TIME: LC_ALL LC_TIME LANG LC_NUMERIC: LC_ALL LC_NUMERIC LANG LC_MONETARY: LC_ALL LC_MONETARY LANG LC_MESSAGES: LC_ALL LC_MESSAGES LANG
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 returned by a prior call to setlocale(LC_ALL ,0). This string will restore each category to the previous locale. If setlocale() fails to set the locale for any category, a null pointer is returned and 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.
It is the user’s responsibility to ensure that mixed locale categories are compatible. For example, setting LC_CTYPE =C and LC_TIME =ja (where ja indicates Japanese) will not work, because Japanese time cannot be represented in the ‘C’ locale’s ASCII codeset.