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fgetwc.3p (4997B)

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.TH FGETWC "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH 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.
.\"
.SH NAME
fgetwc
\(em get a wide-character code from a stream
.SH SYNOPSIS
.LP
.nf
#include <stdio.h>
#include <wchar.h>
.P
wint_t fgetwc(FILE *\fIstream\fP);
.fi
.SH DESCRIPTION
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\(hy2017 defers to the ISO\ C standard.
.P
The
\fIfgetwc\fR()
function shall obtain the next character (if present) from the input
stream pointed to by
.IR stream ,
convert that to the corresponding wide-character code, and advance the
associated file position indicator for the stream (if defined).
.P
If an error occurs, the resulting value of the file position indicator
for the stream is unspecified.
.P
The
\fIfgetwc\fR()
function may mark the last data access timestamp of the file associated
with
.IR stream
for update. The last data access timestamp shall be marked for update
by the first successful execution of
\fIfgetwc\fR(),
\fIfgetws\fR(),
\fIfwscanf\fR(),
\fIgetwc\fR(),
\fIgetwchar\fR(),
\fIvfwscanf\fR(),
\fIvwscanf\fR(),
or
\fIwscanf\fR()
using
.IR stream
that returns data not supplied by a prior call to
\fIungetwc\fR().
.P
The
\fIfgetwc\fR()
function shall not change the setting of
.IR errno
if successful.
.SH "RETURN VALUE"
Upon successful completion, the
\fIfgetwc\fR()
function shall return the wide-character code of the character read from the
input stream pointed to by
.IR stream
converted to a type
.BR 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
\fIfgetwc\fR()
shall return WEOF. If a read error occurs, the error indicator for the
stream shall be set,
\fIfgetwc\fR()
shall return WEOF,
and shall set
.IR errno
to indicate the error.
If an encoding error occurs, the error indicator for the stream
shall be set,
\fIfgetwc\fR()
shall return WEOF, and shall set
.IR errno
to indicate the error.
.SH ERRORS
The
\fIfgetwc\fR()
function shall fail if data needs to be read and:
.TP
.BR EAGAIN
The O_NONBLOCK flag is set for the file descriptor underlying
.IR stream
and the thread would be delayed in the
\fIfgetwc\fR()
operation.
.TP
.BR EBADF
The file descriptor underlying
.IR stream
is not a valid file descriptor open for reading.
.TP
.BR EILSEQ
The data obtained from the input stream does not form a valid
character.
.TP
.BR EINTR
The read operation was terminated due to the receipt of a signal, and
no data was transferred.
.TP
.BR EIO
A physical I/O error has occurred, or the process is in a background
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 implementation-defined reasons.
.TP
.BR EOVERFLOW
The file is a regular file and an attempt was made to read at or beyond
the offset maximum associated with the corresponding stream.
.br
.P
The
\fIfgetwc\fR()
function may fail if:
.TP
.BR ENOMEM
Insufficient storage space is available.
.TP
.BR ENXIO
A request was made of a nonexistent device, or the request was outside
the capabilities of the device.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
The
\fIferror\fR()
or
\fIfeof\fR()
functions must be used to distinguish between an error condition and an
end-of-file condition.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "Section 2.5" ", " "Standard I/O Streams",
.IR "\fIfeof\fR\^(\|)",
.IR "\fIferror\fR\^(\|)",
.IR "\fIfopen\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<stdio.h>\fP",
.IR "\fB<wchar.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
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.opengroup.org/unix/online.html .
.PP
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.kernel.org/doc/man-pages/reporting_bugs.html .