FGETWC(3P) POSIX Programmer's Manual FGETWC(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEfgetwc — get a wide-character code from a stream
wint_t fgetwc(FILE *stream);
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here
and the ISO C standard is unintentional. This volume of POSIX.1‐2008
defers to the ISO C standard.
The fgetwc() function shall obtain the next character (if present) from
the input stream pointed to by stream, convert that to the correspond‐
ing wide-character code, and advance the associated file position indi‐
cator for the stream (if defined).
If an error occurs, the resulting value of the file position indicator
for the stream is unspecified.
The fgetwc() function may mark the last data access timestamp of the
file associated with stream for update. The last data access timestamp
shall be marked for update by the first successful execution of
fgetwc(), fgetws(), fwscanf(), getwc(), getwchar(), vfwscanf(), vws‐
canf(), or wscanf() using stream that returns data not supplied by a
prior call to ungetwc().
The fgetwc() function shall not change the setting of errno if success‐
Upon successful completion, the fgetwc() function shall return the
wide-character code of the character read from the input stream pointed
to by stream converted to a type wint_t. If the end-of-file indicator
for the stream is set, or if the stream is at end-of-file, the end-of-
file indicator for the stream shall be set and fgetwc() shall return
WEOF. If a read error occurs, the error indicator for the stream shall
be set, fgetwc() shall return WEOF, and shall set errno to indicate the
error. If an encoding error occurs, the error indicator for the stream
shall be set, fgetwc() shall return WEOF, and shall set errno to indi‐
cate the error.
The fgetwc() function shall fail if data needs to be read and:
EAGAIN The O_NONBLOCK flag is set for the file descriptor underlying
stream and the thread would be delayed in the fgetwc() opera‐
EBADF The file descriptor underlying stream is not a valid file
descriptor open for reading.
EILSEQ The data obtained from the input stream does not form a valid
EINTR The read operation was terminated due to the receipt of a sig‐
nal, and no data was transferred.
EIO A physical I/O error has occurred, or the process is in a back‐
ground process group attempting to read from its controlling
terminal, and either the calling thread is blocking SIGTTIN or
the process is ignoring SIGTTIN or the process group of the
process is orphaned. This error may also be generated for
The file is a regular file and an attempt was made to read at or
beyond the offset maximum associated with the corresponding
The fgetwc() function may fail if:
ENOMEM Insufficient storage space is available.
ENXIO A request was made of a nonexistent device, or the request was
outside the capabilities of the device.
The following sections are informative.
The ferror() or feof() functions must be used to distinguish between an
error condition and an end-of-file condition.
Section 2.5, Standard I/O Streams, feof(), ferror(), fopen()
The Base Definitions volume of POSIX.1‐2008, <stdio.h>, <wchar.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
IEEE/The Open Group 2013 FGETWC(3P)