The putwc() function shall be equivalent to fputwc(), except that
if it is implemented as a macro it may evaluate stream more than once,
so the argument should never be an expression with side effects.
Since it may be implemented as a macro, putwc() may treat a stream
argument with side effects incorrectly. In particular,
putwc(wc,* f++) need not work correctly. Therefore, use
of this function is not recommended; fputwc() should be used instead.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html