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std::ungetwc(3)		      C++ Standard Libary	       std::ungetwc(3)

NAME
       std::ungetwc - std::ungetwc

Synopsis
	  Defined in header <cwchar>
	  wint_t ungetwc( wint_t ch, std::FILE*	stream );

	  If ch	does not equal WEOF, pushes the	wide character ch into the in-
       put buffer
	  associated  with  the	stream stream in such a	manner than subsequent
       read operation
	  from stream will retrieve that wide character. The  external	device
       associated with
	  the stream is	not modified.

	  Stream   repositioning   operations  std::fseek,  std::fsetpos,  and
       std::rewind discard
	  the effects of ungetwc.

	  If ungetwc is	called more than once without an intervening  read  or
       repositioning, it
	  may fail (in other words, a pushback buffer of size 1	is guaranteed,
       but any larger
	  buffer  is  implementation-defined).	If multiple successful ungetwc
       were performed,
	  read operations retrieve the pushed-back wide	characters in  reverse
       order of	ungetwc

	  If  ch  equals  WEOF,	 the operation fails and the stream is not af-
       fected.

	  A successful call to ungetwc clears the  end	of  file  status  flag
       feof.

	  A  successful	 call  to ungetwc on a stream (whether text or binary)
       modifies	the
	  stream position indicator in unspecified manner but guarantees  that
       after all
	  pushed-back wide characters are retrieved with a read	operation, the
       stream position
	  indicator is equal to	its value before ungetwc.

Parameters
	  ch	 - wide	character to be	put back
	  stream - file	stream to put the wide character back to

Return value
	  On success ch	is returned.

	  On failure WEOF is returned and the given stream remains unchanged.

See also
	  ungetc puts a	character back into a file stream
		 (function)
	  fgetwc gets a	wide character from a file stream
	  getwc	 (function)

http://cppreference.com		  2022.07.31		       std::ungetwc(3)

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