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 failure.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(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 current locale.

SEE ALSO

       fgetwc(3)