GENWiki

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 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
     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 cur-
     rent locale.