NAME

       ungetwc - push wide-character code back into the input stream

SYNOPSIS

       #include <stdio.h>
       #include <wchar.h>

       wint_t ungetwc(wint_t wc, FILE *stream);

DESCRIPTION

       The  ungetwc() function shall push the character corresponding to the wide-character code specified by wc
       back onto the input stream pointed to  by  stream.  The  pushed-back  characters  shall  be  returned  by
       subsequent  reads  on  that  stream  in the reverse order of their pushing. A successful intervening call
       (with the stream pointed to by stream) to a file-positioning function ( fseek(), fsetpos(), or  rewind())
       discards  any  pushed-back characters for the stream. The external storage corresponding to the stream is
       unchanged.

       At least one character of push-back shall be provided. If ungetwc() is called too many times on the  same
       stream without an intervening read or file-positioning operation on that stream, the operation may fail.

       If  the value of wc equals that of the macro WEOF, the operation shall fail and the input stream shall be
       left unchanged.

       A successful call to ungetwc() shall clear the end-of-file indicator for the stream.  The  value  of  the
       file-position  indicator  for  the stream after reading or discarding all pushed-back characters shall be
       the same as it was before the characters were pushed back. The file-position indicator is decremented (by
       one or more) by each successful call to ungetwc(); if its value  was  0  before  a  call,  its  value  is
       unspecified after the call.

RETURN VALUE

       Upon  successful  completion, ungetwc() shall return the wide-character code corresponding to the pushed-
       back character.  Otherwise, it shall return WEOF.

ERRORS

       The ungetwc() function may fail if:

       EILSEQ An invalid character sequence is detected, or a wide-character code does not correspond to a valid
              character.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fseek() , fsetpos() , read() , rewind() , setbuf() , the Base Definitions volume of IEEE Std 1003.1-2001,
       <stdio.h>, <wchar.h>

COPYRIGHT

       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 .

IEEE/The Open Group                                   2003                                            UNGETWC(P)