The fputwc function is the wide-character equivalent of the fputc
function. It writes the wide character wc to stream. If
ferror(stream) becomes true, it returns WEOF. If a wide character
conversion error occurs, it sets errno to EILSEQ and returns
WEOF. Otherwise it returns wc.
The putwc function or macro functions identically to fputwc. It
may be implemented as a macro, and may evaluate its argument more than once.
There is no reason ever to use it.
For non-locking counterparts, see unlocked_stdio(3).
The behaviour of fputwc depends on the LC_CTYPE category of the current
In the absence of additional information passed to the fopen call, it is
reasonable to expect that fputwc will actually write the multibyte
sequence corresponding to the wide character wc.