#define USE_XOPEN_SOURCE

#include <stdio.h>
#include <locale.h>
#ifdef USE_XOPEN_SOURCE
#  include <langinfo.h>
#endif
#include <X11/Xlib.h>
#include <X11/Xlocale.h>

main()
{
    printf("LC_CTYPE = %s\n", setlocale(LC_CTYPE, ""));
#ifdef USE_XOPEN_SOURCE
    printf("encoding = %s\n", nl_langinfo(CODESET));
#endif
    if (XSupportsLocale() == True)
        printf("X Locale = OK\n");
}