ungetwc(3) Library Functions Manual ungetwc(3)
NAME
ungetwc - push back a wide character onto a FILE stream
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <wchar.h>
wint_t ungetwc(wint_t wc, FILE *stream);
DESCRIPTION
The ungetwc() function is the wide-character equivalent of the
ungetc(3) function. It pushes back a wide character onto stream and
returns it.
If wc is WEOF, it returns WEOF. If wc is an invalid wide character, it
sets errno to EILSEQ and returns WEOF.
If wc is a valid wide character, it is pushed back onto the stream and
thus becomes available for future wide-character read operations. The
file-position indicator is decremented by one or more. The end-of-file
indicator is cleared. The backing storage of the file is not affected.
Note: wc need not be the last wide-character read from the stream; it
can be any other valid wide character.
If the implementation supports multiple push-back operations in a row,
the pushed-back wide characters will be read in reverse order; however,
only one level of push-back is guaranteed.
RETURN VALUE
The ungetwc() function returns wc when successful, or WEOF upon fail-
ure.
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌───────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────────────────┼───────────────┼─────────┤
│ ungetwc() │ Thread safety │ MT-Safe │
└───────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
C11, POSIX.1-2008.
HISTORY
POSIX.1-2001, C99.
NOTES
The behavior of ungetwc() depends on the LC_CTYPE category of the cur-
rent locale.
SEE ALSO
fgetwc(3)
Linux man-pages 6.7 2023-10-31 ungetwc(3)
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