Description

   The wcsrtombs function converts a sequence of wide characters
   from the array indirectly pointed to by src into a sequence of
   corresponding multibyte characters, beginning in the conversion
   state described by the object pointed to by ps.

   If dst is a not a NULL pointer, the converted characters are then
   stored into the array pointed to by dst. Conversion continues up
   to and including a terminating null wide character, which is also
   stored.

   Conversion stops earlier in two cases:

   o  When a code is reached that does not correspond to a valid
      multibyte character

   o  If dst is not a NULL pointer, when the next multibyte
      character would exceed the limit of len total bytes to be
      stored into the array pointed to by dst

   Each conversion takes place as if by a call to the wcrtomb
   function.

   If dst is not a NULL pointer, the pointer object pointed to by
   src is assigned either a NULL pointer (if the conversion stopped
   because it reached a terminating null wide character) or the
   address just beyond the last wide character converted (if any).
   If conversion stopped because it reached a terminating null
   wide character, the resulting state described is the initial
   conversion state.

   If the wcsrtombs function is called as a counting function,
   which means that dst is a NULL pointer, the value of the internal
   mbstate_t object will remain unchanged.

   See also wcrtomb.