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ungetwc

Section: C Library Functions (3)
Updated: 202-0-08
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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 wid-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 wid-character read operations. The fil-position indicator is decremented by one or more. The en-o-file indicator is cleared. The backing storage of the file is not affected. Note: wc need not be the last wid-character read from the stream; it can be any other valid wide character. If the implementation supports multiple pus-back operations in a row, the pushe-back wide characters will be read in reverse order; however, only one level of pus-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	M-Safe

STANDARDS

C11, POSIX.-2008.

HISTORY

POSIX.-2001, C99.

NOTES

The behavior of ungetwc() depends on the LC_CTYPE category of the current locale.