NAME
ungetwc() — push a wide character back into an input stream
SYNOPSIS
#include <wchar.h>
wint_t ungetwc(wint_t wc, FILE *stream);
Obsolescent Interface
wint_t ungetwc_unlocked(wint_t wc, FILE *stream);
Remarks:
This function is compliant with the
XPG4
Worldwide Portability Interface wide-character
I/O
functions.
It parallels the 8-bit character
I/O
function defined in
ungetc(3S).
DESCRIPTION
ungetwc()
pushes the character corresponding to the wide-character code
wc
into the buffer associated with an input
stream.
That wide-character code,
wc,
is returned by the next call to
getwc()
(see
getwc(3C))
on that
stream.
A successful intervening call to a file positioning function with
stream
(fseek(),
fsetpos(),
or
rewind())
erases all memory of the pushed-back characters.
ungetwc()
affects only the buffer associated with the input
stream.
It does not affect the contents of the file corresponding to
stream.
One character of pushback is guaranteed.
If
wc
equals
WEOF,
ungetwc()
does nothing to the buffer and returns
WEOF.
The definition for this function, the type
wint_t
and the value
WEOF
are provided in the
<wchar.h>
header.
Obsolescent Interface
ungetwc_unlocked()
pushes a wide character back into an input stream.
APPLICATION USAGE
ungetwc()
is a thread-safe interface. It is not async-cancel-safe. A cancellation
point may occur when a thread is executing
ungetwc().
EXTERNAL INFLUENCES
Locale
The
LC_CTYPE
category determines how wide character conversions are done.
International Code Set Support
Single- and multi-byte character code sets are supported.
RETURN VALUE
If successful,
ungetwc() and ungetwc_unlocked()
return
wc
and clear the end-of-file indicator for the stream.
ungetwc() and ungetwc_unlocked()
return
WEOF
if they cannot insert the wide character.
WARNINGS
ungetwc_unlocked()
is an obsolescent interface supported only for compatibility with
existing DCE applications. New multithreaded applications should use
ungetwc().
AUTHOR
ungetwc()
and
ungetwc_unlocked()
were developed by OSF and HP.
STANDARDS CONFORMANCE
ungetwc(): XPG4
