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)