wistream wcin;
After the object wcin is initialized, wcin.tie() returns &wcout. Its state is otherwise the same as required for basic_ios<wchar_t>::init.
wostream wcout;
wostream wcerr;
After the object wcerr is initialized, wcerr.flags() & unitbuf is nonzero and wcerr.tie() returns &wcout. Its state is otherwise the same as required for basic_ios<wchar_t>::init.
wostream wclog;