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UNGETWC(3) Linux Programmer's Manual UNGETWC(3)
NAME
ungetwc - push back a wide character onto a FILE stream
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 indi‐
cator 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 failure.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
│ungetwc() │ Thread safety │ MT-Safe │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, C99.
NOTES
The behavior of ungetwc() depends on the LC_CTYPE category of the current locale.
SEE ALSO
fgetwc(3)
GNU 2021-03-22 UNGETWC(3)