setlocale - set the current locale

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────────────────────────────────────────────────┬───────────────┬────────────────────────────┐
       │ Interface                                                │ Attribute     │ Value                      │
       ├──────────────────────────────────────────────────────────┼───────────────┼────────────────────────────┤
       │ setlocale()                                              │ Thread safety │ MT-Unsafe const:locale env │
       └──────────────────────────────────────────────────────────┴───────────────┴────────────────────────────┘

       The setlocale() function is used to set or query the program's current locale.

       If locale is not NULL, the program's current locale is modified according to the arguments.  The argument
       category determines which parts of the program's current locale should be modified.
       CategoryGovernsLC_ALL              All of the locale
       LC_ADDRESS          Formatting of addresses and geography-related items (*)
       LC_COLLATE          String collation
       LC_CTYPE            Character classification
       LC_IDENTIFICATION   Metadata describing the locale (*)
       LC_MEASUREMENT      Settings related to measurements (metric versus US customary) (*)
       LC_MESSAGES         Localizable natural-language messages
       LC_MONETARY         Formatting of monetary values
       LC_NAME             Formatting of salutations for persons (*)
       LC_NUMERIC          Formatting of nonmonetary numeric values
       LC_PAPER            Settings related to the standard paper size (*)
       LC_TELEPHONE        Formats to be used with telephone services (*)
       LC_TIME             Formatting of date and time values

       The categories marked with an asterisk in the above table are GNU extensions.  For further information on
       these locale categories, see locale(7).

       The argument locale is a pointer to a character string containing the required setting of category.  Such
       a  string  is  either a well-known constant like "C" or "da_DK" (see below), or an opaque string that was
       returned by another call of setlocale().

       If locale is an empty string, "", each part of the locale that should be modified is set according to the
       environment variables.  The details  are  implementation-dependent.   For  glibc,  first  (regardless  of
       category), the environment variable LC_ALL is inspected, next the environment variable with the same name
       as  the  category  (see  the table above), and finally the environment variable LANG.  The first existing
       environment variable is used.  If its value is not a valid locale specification, the locale is unchanged,
       and setlocale() returns NULL.

       The locale "C" or "POSIX" is a portable locale; it exists on all conforming systems.

       A locale name is typically of the form language[_territory][.codeset][@modifier], where  language  is  an
       ISO  639 language code, territory is an ISO 3166 country code, and codeset is a character set or encoding
       identifier like ISO-8859-1 or UTF-8.  For  a  list  of  all  supported  locales,  try  "locale  -a"  (see
       locale(1)).

       If locale is NULL, the current locale is only queried, not modified.

       On  startup  of  the main program, the portable "C" locale is selected as default.  A program may be made
       portable to all locales by calling:

           setlocale(LC_ALL, "");

       after program initialization, and then:

       •  using the values returned from a localeconv(3) call for locale-dependent information;

       •  using the multibyte and wide character functions for text processing if MB_CUR_MAX>1;

       •  using strcoll(3) and strxfrm(3) to compare strings; and

       •  using wcscoll(3) and wcsxfrm(3) to compare wide-character strings.

       POSIX.1-2001, C89.

   CategoriesLC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME
              C89, POSIX.1-2001.

       LC_MESSAGES
              POSIX.1-2001.

       Others:
              GNU.

       Standard C library (libc, -lc)

       setlocale - set the current locale

       A successful call to setlocale() returns an opaque string that  corresponds  to  the  locale  set.   This
       string  may be allocated in static storage.  The string returned is such that a subsequent call with that
       string and its associated category will restore that part of the process's locale.  The return  value  is
       NULL if the request cannot be honored.

locale(1),  localedef(1), isalpha(3), localeconv(3), nl_langinfo(3), rpmatch(3), strcoll(3), strftime(3),
       charsets(7), locale(7)

Linux man-pages 6.9.1                              2024-05-02                                       setlocale(3)

       C11, POSIX.1-2008.

   CategoriesLC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME
              C11, POSIX.1-2008.

       LC_MESSAGES
              POSIX.1-2008.

       Others:
              GNU.

#include<locale.h>char*setlocale(intcategory,constchar*locale);