const char hello[] = "hello";
lua_pushlstring(s, hello, 4); // actually stores "hell"

const char * pstr = lua_tostring(s, -1);

   const wchar_t str1[] = L"HELLO";
   const wchar_t str2[] = L"DOLLY";
   lua_getglobal(s, "strcat");
   lua_pushlstring(s, reinterpret_cast<const char *>(str1), ::wcslen(str1) * sizeof(wchar_t));
   lua_pushlstring(s, reinterpret_cast<const char *>(str2), ::wcslen(str2) * sizeof(wchar_t));
   lua_call(s, 2, 1);
   size_t len;
   const wchar_t * pstr = reinterpret_cast<const wchar_t *>(lua_tolstring(s, -1, &len));
   ::std::wstring str(pstr, len);

function strcat(s1, s2) return s1 .. s2 end