If a valid locale and category are given, returns a pointer to the string associated with the specified locale and category. If the locale or category is invalid, returns a null pointer and the current locale settings of the program are not changed.

For example, the call

setlocale( LC_ALL, "English" );

sets all categories, returning only the string

English_United States.1252

If all categories are not explicitly set by a call to setlocale, the function returns a string indicating the current setting of each of the categories, separated by semicolons. If the locale argument is a null pointer, setlocale returns a pointer to the string associated with the category of the program's locale; the program's current locale setting is not changed.

The null pointer is a special directive that tells setlocale to query rather than set the international environment. For example, the sequence of calls

// Set all categories and return " English_United States.1252"

setlocale( LC_ALL, "English" );

// Set only the LC_MONETARY category and return "French_France.1252"

setlocale( LC_MONETARY, "French" );

setlocale( LC_ALL, NULL );

returns

LC_COLLATE= English_United States.1252;

LC_CTYPE= English_United States.1252;

LC_MONETARY=French_France.1252;

LC_NUMERIC= English_United States.1252;

LC_TIME= English_United States.1252

which is the string associated with the LC_ALL category.

One can use the string pointer returned by setlocale in subsequent calls to restore that part of the program's locale information, assuming that your program does not alter the pointer or the string. Later calls to setlocale overwrite the string; you can use _strdup to save a specific locale string.

Use the setlocale function to set, change, or query some or all of the current program locale information specified by locale and category. locale refers to the locality (country/region and language) for which you can customize certain aspects of your program. Some locale-dependent categories include the formatting of dates and the display format for monetary values. If you set locale to the default string for a language with multiple forms supported on your computer, you should check the setlocale return code to see which language is in effect. For example, using "chinese" could result in a return value of chinese-simplified or chinese-traditional.

_wsetlocale is a wide-character version of setlocale; the locale argument and return value of _wsetlocale are wide-character strings. _wsetlocale and setlocale behave identically otherwise.

The category argument specifies the parts of a program's locale information that are affected. The macros used for category and the parts of the program they affect are as follows:

LC_ALL

All categories, as listed below.

LC_COLLATE

The strcoll, _stricoll, wcscoll, _wcsicoll, strxfrm, _strncoll, _strnicoll, _wcsncoll, _wcsnicoll, and wcsxfrm functions.

LC_CTYPE

The character-handling functions (except isdigit, isxdigit, mbstowcs, and mbtowc, which are unaffected).

LC_MONETARY

Monetary-formatting information returned by the localeconv function.

LC_NUMERIC

Decimal-point character for the formatted output routines (such as printf), for the data-conversion routines, and for the non-monetary formatting information returned by localeconv.    In addition to the decimal-point character, LC_NUMERIC also sets the thousands separator and the grouping control string returned by localeconv.

LC_TIME

The strftime and wcsftime functions.

This function validates the category parameter. If the category parameter is not one of the values given in the above table, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, the function sets errno to EINVAL and returns NULL.

The locale argument is a pointer to a string that specifies the name of the locale. If locale points to an empty string, the locale is the implementation-defined native environment. A value of C specifies the minimal ANSI conforming environment for C translation. The C locale assumes that all char data types are 1 byte and that their value is always less than 256.

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

setlocale( LC_ALL, "C" );

The locale argument takes the following form:

locale :: "lang[_country_region[.code_page]]"

| ".code_page"

| ""

| NULL

The set of available languages, country/region codes, and code pages includes all those supported by the Win32 NLS API except code pages that require more than two bytes per character, such as UTF-7 and UTF-8. If you provide a code page like UTF-7 or UTF-8, setlocale will fail, returning NULL. The set of language and country/region codes supported by setlocale is listed in Language and Country/Region Strings.

If locale is a null pointer, setlocale queries, rather than sets, the international environment and returns a pointer to the string associated with the specified category. The program's current locale setting is not changed. For example,

setlocale( LC_ALL, NULL );

returns the string associated with category.

The following examples pertain to the LC_ALL category. Either of the strings ".OCP" and ".ACP" can be used in place of a code page number to specify use of the user-default OEM code page and user-default ANSI code page, respectively.

setlocale( LC_ALL, "" );

Sets the locale to the default, which is the user-default ANSI code page obtained from the operating system.

setlocale( LC_ALL, ".OCP" );

Explicitly sets the locale to the current OEM code page obtained from the operating system.

setlocale( LC_ALL, ".ACP" );

Sets the locale to the ANSI code page obtained from the operating system.

setlocale( LC_ALL, "[lang_ctry]" );

Sets the locale to the language and country/region indicated, using the default code page obtained from the host operating system.

setlocale( LC_ALL, "[lang_ctry.cp]" );

Sets the locale to the language, country/region, and code page indicated in the [lang_ctry.cp] string. You can use various combinations of language, country/region, and code page. For example:

setlocale( LC_ALL, "French_Canada.1252" );
// Set code page to French Canada ANSI default
setlocale( LC_ALL, "French_Canada.ACP" );
// Set code page to French Canada OEM default
setlocale( LC_ALL, "French_Canada.OCP" );

setlocale( LC_ALL, "[lang]" );

Sets the locale to the country/region indicated, using the default country/region for the language specified, and the user-default ANSI code page for that country/region as obtained from the host operating system. For example, the following two calls to setlocale are functionally equivalent:

setlocale( LC_ALL, "English" );
setlocale( LC_ALL, "English_United States.1252" );

setlocale( LC_ALL, "[.code_page]" );

Sets the code page to the value indicated, using the default country/region and language (as defined by the host operating system) for the specified code page.

The category must be either LC_ALL or LC_CTYPE to effect a change of code page. For example, if the default country/region and language of the host operating system are "United States" and "English," the following two calls to setlocale are functionally equivalent:

setlocale( LC_ALL, ".1252" );

setlocale( LC_ALL, "English_United States.1252");

For more information see the setlocale pragma in the Preprocessor Reference.

The function _configthreadlocale is used to control whether setlocale affects the locale of all threads in a program or only the locale of the calling thread.

For additional compatibility information, see Compatibility in the Introduction.

// crt_setlocale.cpp
// 
// This program demonstrates the use of setlocale when
// using two independent threads.
//

#include <locale.h>
#include <process.h>
#include <windows.h>
#include <stdio.h>
#include <time.h>

#define BUFF_SIZE 100

// Retrieve the date and time in the current
// locale's format.
int get_time(unsigned char* str)
{
    __time64_t ltime;
    struct tm  thetime;

    // Retieve the time
    _time64(&ltime);
    _gmtime64_s(&thetime, &ltime);

    // Format the current time structure into a string
    // using %#x is the long date representation,
    // appropriate to the current locale
    if (!strftime((char *)str, BUFF_SIZE, "%#x", 
                  (const struct tm *)&thetime))
    {
        printf("strftime failed!\n");
        return -1;
    }
    return 0;
}

// This thread sets its locale to German
// and prints the time.
unsigned __stdcall SecondThreadFunc( void* pArguments )
{
    unsigned char str[BUFF_SIZE];

    // Set the thread local
    printf("The thread locale is now set to %s.\n",
           setlocale(LC_ALL, "German"));

    // Retrieve the time string from the helper function
    if (get_time(str) == 0)
    {
        printf("The time in German locale is: '%s'\n", str);
    }

    _endthreadex( 0 );
    return 0;
} 

// The main thread spawns a second thread (above) and then
// sets the locale to English and prints the time.
int main()
{ 
    HANDLE          hThread;
    unsigned        threadID;
    unsigned char   str[BUFF_SIZE];

    // Configure per-thread locale to cause all subsequently created 
    // threads to have their own locale.
    _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);

    // Retrieve the time string from the helper function
    printf("The thread locale is now set to %s.\n",
           setlocale(LC_ALL, "English"));

    // Create the second thread.
    hThread = (HANDLE)_beginthreadex( NULL, 0, &SecondThreadFunc,
                                      NULL, 0, &threadID );

    if (get_time(str) == 0)
    {
        // Retrieve the time string from the helper function
        printf("The time in English locale is: '%s'\n\n", str);
    }

    // Wait for the created thread to finish.
    WaitForSingleObject( hThread, INFINITE );

    // Destroy the thread object.
    CloseHandle( hThread );
}

Sample Output

The thread locale is now set to English_United States.1252.
The time in English locale is: 'Wednesday, May 12, 2004'

The thread locale is now set to German_Germany.1252.
The time in German locale is: 'Mittwoch, 12. Mai 2004'

System::Globalization::CultureInfo Class

Reference