FERROR(3) Linux Programmer's Manual FERROR(3)
NAME
clearerr, feof, ferror, fileno - check and reset stream status
SYNOPSIS
#include <stdio.h>
void clearerr(FILE *stream);
int feof(FILE *stream);
int ferror(FILE *stream);
int fileno(FILE *stream);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
fileno(): _POSIX_C_SOURCE
DESCRIPTION
The function clearerr() clears the end-of-file and error indicators for
the stream pointed to by stream.
The function feof() tests the end-of-file indicator for the stream
pointed to by stream, returning nonzero if it is set. The end-of-file
indicator can be cleared only by the function clearerr().
The function ferror() tests the error indicator for the stream pointed
to by stream, returning nonzero if it is set. The error indicator can
be reset only by the clearerr() function.
The function fileno() examines the argument stream and returns the in-
teger file descriptor used to implement this stream. The file descrip-
tor is still owned by stream and will be closed when fclose(3) is
called. Duplicate the file descriptor with dup(2) before passing it to
code that might close it.
For nonlocking counterparts, see unlocked_stdio(3).
ERRORS
These functions should not fail and do not set the external variable
errno. (However, in case fileno() detects that its argument is not a
valid stream, it must return -1 and set errno to EBADF.)
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+--------------------+---------------+---------+
|Interface | Attribute | Value |
+--------------------+---------------+---------+
|clearerr(), feof(), | Thread safety | MT-Safe |
|ferror(), fileno() | | |
+--------------------+---------------+---------+
CONFORMING TO
The functions clearerr(), feof(), and ferror() conform to C89, C99,
POSIX.1-2001, and POSIX.1-2008.
The function fileno() conforms to POSIX.1-2001 and POSIX.1-2008.
SEE ALSO
open(2), fdopen(3), stdio(3), unlocked_stdio(3)
COLOPHON
This page is part of release 5.07 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2019-03-06 FERROR(3)