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OpenSolaris 2009.06 - man page for ungetwc (opensolaris section 3c)

ungetwc(3C)						   Standard C Library Functions 					       ungetwc(3C)

NAME
ungetwc - push wide-character code back into input stream
SYNOPSIS
#include <stdio.h> #include <wchar.h> wint_t ungetwc(wint_t wc, FILE *stream);
DESCRIPTION
The ungetwc() function pushes the character corresponding to the wide character code specified by wc back onto the input stream pointed to by stream. The pushed-back characters will be returned by subsequent reads on that stream in the reverse order of their pushing. A success- ful intervening call (with the stream pointed to by stream) to a file-positioning function ( fseek(3C), fsetpos(3C) or rewind(3C)) discards any pushed-back characters for the stream. The external storage corresponding to the stream is unchanged. One character of push-back is guaranteed. 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 fails and the input stream is unchanged. A successful call to ungetwc() clears 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 will 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 indetermi- nate after the call.
RETURN VALUES
Upon successful completion, ungetwc() returns the wide-character code corresponding to the pushed-back character. Otherwise it returns 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.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ |ATTRIBUTE TYPE |ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+
SEE ALSO
read(2), fseek(3C), fsetpos(3C), rewind(3C), setbuf(3C), attributes(5), standards(5) SunOS 5.11 14 Aug 2002 ungetwc(3C)