IOS / Mac OSX :
=============

#include <CoreFoundation/CoreFoundation.h>

    CFArrayRef localeIDs = CFLocaleCopyPreferredLanguages();
    char tmp[16];
    if (localeIDs)
    {
       CFStringRef localeID = (CFStringRef)CFArrayGetValueAtIndex(localeIDs, 0);
 
       if (CFStringGetCString(localeID, tmp, 16, kCFStringEncodingUTF8))
       {
          str = tmp; // Get the locale in the variable "tmp".
       }
       CFRelease(localeIDs);
    }


WinRT / Windows 8 / Window Phone
================================

using namespace Windows::Graphics::Display;
# include <wchar.h>


   char _buffer[128] = "";
   char _buffer2[128] = "";
   int ret = 0;

# if WINAPI_FAMILY == WINAPI_FAMILY_PHONE_APP
   ret = GetLocaleInfoEx(LOCALE_NAME_SYSTEM_DEFAULT, LOCALE_SNAME, (LPWSTR)_buffer, 32);
# else
   ret = GetSystemDefaultLocaleName((LPWSTR)_buffer, 32);
# endif

   if (ret > 0)
   {
      // Need to conver LPWSTR to LPSTR, that is wide char to char.
      str = _buffer2;
      memset(_buffer2, 0, sizeof(_buffer2));
      if (ret > 32)
      {
         ret = 32;
      }
      for (int i = 0; i < ret; i++)
      {
         _buffer2[i] = _buffer[2 * i];
      }
   }

Android 
========


// Java :

 
public static String     str_language           = "";

...

in the constructor : 

      try
      {
         String lang = new String(Locale.getDefault().getLanguage());
         if (Locale.getDefault().getCountry().length() > 0)
         {
            lang = lang + "_" + Locale.getDefault().getCountry();
         }

         str_language = lang;
      }
      catch (Exception e)
      {
      }

      try
      {
         System.out.println("libSDL: setting envvar LANGUAGE to '" + str_language + "'");
      }
      catch (Exception e)
      {
      }


...

// a function to access from Native Code
public static String getLANG()
{
    return str_language;
}


+ Native code to get the language string (to be re-written) :


   JNI_FIND_CLASS(MainActivity_class, TOSTRING(SL_PACKAGE) "/MainActivity");
   JNI_FIND_METHOD_STATIC(methodId, MainActivity_class, "getLANG", "()Ljava/lang/String;");
   jstring jstr = (jstring) JavaEnv()->CallStaticObjectMethod(MainActivity_class, methodId);

   check_exception();

   if (jstr == 0)
   {
      // Clean
      JavaEnv()->DeleteLocalRef(MainActivity_class);
      return -1;
   }

   // Get Native String
   const char *tmp_str = JavaEnv()->GetStringUTFChars(jstr, 0);
   if (tmp_str == NULL)
   {
      // Clean
      JavaEnv()->DeleteLocalRef(jstr);
      JavaEnv()->DeleteLocalRef(MainActivity_class);
      return -1;
   }

   // Length truncate
   int tmp_len = strlen(tmp_str);
   if (tmp_len > len)
   {
      tmp_len = len;
   }

   // Copy
   memset(buf, 0, len);
   memcpy(buf, tmp_str, tmp_len);

   // Clean
   JavaEnv()->ReleaseStringUTFChars(jstr, tmp_str);
   JavaEnv()->DeleteLocalRef(jstr);
   JavaEnv()->DeleteLocalRef(MainActivity_class);



Else (linux, nacl):
=======

   str = getenv("LANG");