LC_ALL, LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME

Each of the above macro constants expand to integer constant expressions with distinct values that are suitable for use as the first argument of setlocale .

Additional macro constants, with names that begin with LC_ followed by at least one uppercase letter, may be defined in locale.h . For example, the POSIX specification requires LC_MESSAGES (which controls, among other things, perror and strerror ), ISO/IEC 30112:2014 ( 2014 draft ) additionally defines LC_IDENTIFICATION , LC_XLITERATE , LC_NAME , LC_ADDRESS , LC_TELEPHONE , LC_PAPER , LC_MEASUREMENT , and LC_KEYBOARD , which are supported by the GNU C library (except for LC_XLITERATE ).

Example

#include <locale.h>
#include <stdio.h>
#include <time.h>
#include <wchar.h>
 
int main(void)
{
    setlocale(LC_ALL, "en_US.UTF-8"); // the C locale will be the UTF-8 enabled English
    setlocale(LC_NUMERIC, "de_DE.utf8"); // decimal dot will be German
    setlocale(LC_TIME, "ja_JP.utf8");    // date/time formatting will be Japanese
    wchar_t str[100];
    time_t t = time(NULL);
    wcsftime(str, 100, L"%A %c", localtime(&t));
    wprintf(L"Number: %.2f\nDate: %Ls\n", 3.14, str);
}

Number: 3,14
Date: 金曜日 2023年09月15日 20時04分14秒

References

See also