Return_Values

   x                  Number of nonidentical conversions performed.
                      Indicates successful conversion. In most
                      cases, 0 is returned.
   (size_t) -1        Indicates an error condition. The function
                      sets errno to one of the following:

                      o  EBADF - The cd argument is not a valid
                         conversion descriptor.

                      o  EILSEQ - The conversion stops when an
                         invalid character detected.

                      o  E2BIG - The conversion stops because of
                         insufficient space in the output buffer.

                      o  EINVAL - The conversion stops because of
                         an incomplete character at the end of the
                         input buffer.