Sun Microsystems, Inc. gratefully acknowledges The Open Group for
permission to reproduce portions of its copyrighted documentation.
Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.
The Institute of Electrical and Electronics Engineers and The Open
Group, have given us permission to reprint portions of their
documentation.
In the following statement, the phrase ``this text'' refers to portions
of the system documentation.
Portions of this text are reprinted and reproduced in electronic form
in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6,
Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy
between these versions 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.
This notice shall appear on any product containing this material.
The contents of this file are subject to the terms of the
Common Development and Distribution License (the "License").
You may not use this file except in compliance with the License.
You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
or http://www.opensolaris.org/os/licensing.
See the License for the specific language governing permissions
and limitations under the License.
When distributing Covered Code, include this CDDL HEADER in each
file and include the License file at usr/src/OPENSOLARIS.LICENSE.
If applicable, add the following below this CDDL HEADER, with the
fields enclosed by brackets "[]" replaced with your own identifying
information: Portions Copyright [yyyy] [name of copyright owner]
Copyright (c) 1992, X/Open Company Limited. All Rights Reserved.
Portions Copyright (c) 2002, Sun Microsystems, Inc. All Rights Reserved
#include <stdio.h> #include <wchar.h> wint_t ungetwc(wint_t wc, FILE *stream);
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 successful 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 indeterminate after the call.
Upon successful completion, ungetwc() returns the wide-character code corresponding to the pushed-back character. Otherwise it returns WEOF.
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.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE ATTRIBUTE VALUE |
| Interface Stability Standard |
| MT-Level MT-Safe |
read(2), fseek(3C), fsetpos(3C), rewind(3C), setbuf(3C), attributes(5), standards(5)