size_t mbsrtowcs (wchar_t *, const char **, size_t, mbstate_t *);
size_t wcsrtombs (char *, const wchar_t **, size_t, mbstate_t *);
size_t mbsrtowcs (wchar_t *, const char **, size_t, mbstate_t *);
size_t wcsrtombs (char *, const wchar_t **, size_t, mbstate_t *);