Description

   If the current locale does not have language information defined,
   the function returns information from the C locale. The program
   should not modify the string returned by the function. This
   string might be overwritten by subsequent calls to nl_langinfo.

   If the setlocale function is called after a call to nl_langinfo,
   then the pointer returned by the previous call to nl_langinfo
   will be unspecified. In this case, the nl_langinfo function
   should be called again.