_vvvv_ffff_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff places output on the named output _s_t_r_e_a_m.
_vvvv_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff places output on _ssss_tttt_dddd_oooo_uuuu_tttt.
_vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff places output, followed by a null wide-character in consecutive
wide-characters starting at *_s; no more than _n wide-characters are
written, including a terminating null wide-character, which is always
added (unless n is zero).
Each function returns the number of wide-characters transmitted (not
including the terminating null character in the case of _vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff), or a
negative value if an output error was encountered. If n or more wide
characters were requested to be written _vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))) returns a negative
value.
The _vvvv_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))), _vvvv_ffff_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))) and _vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))) functions are the same as
_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))), _ffff_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))) and _ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))) respectively, except that instead of
being called with a variable number of arguments, they are called with an
argument list as defined by <stdarg.h>.
These functions do not invoke the va_end macro. However, as these
functions do invoke the va_arg macro, the value of ap after the return is
indeterminate.
EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS
The following example shows the use of the vfwprintf function in a
_vvvv_ffff_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff, _vvvv_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff, and _vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff return the number of wide-characters
transmitted (not counting the terminating null character for _vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff),
or return a negative value if an error was encountered. If _n or more
wide characters were requested to be written _vvvv_ssss_wwww_pppp_rrrr_iiii_nnnn_tttt_ffff_((((_)))) returns a
negative value.
In addition, all forms of vfwprintf() may fail if:
[EILSEQ]
A wide-character code that does not correspond to a valid
character has been detected.
[EINVAL]
There are insufficient arguments.
In addition, vwprintf() and vfwprintf() may fail if: