ferror
Section: C Library Functions (3)
Updated: 2022-12-29
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NAME
clearerr, feof, ferror - check and reset stream status
LIBRARY
Standard C library
(libc, -lc)
SYNOPSIS
#include <stdio.h>
void clearerr(FILE *stream);
int feof(FILE *stream);
int ferror(FILE *stream);
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.
For nonlocking counterparts, see
unlocked_stdio(3).
RETURN VALUE
The
feof()
function returns nonzero if the end-of-file indicator is set for
stream;
otherwise, it returns zero.
The
ferror()
function returns nonzero if the error indicator is set for
stream;
otherwise, it returns zero.
ERRORS
These functions should not fail and do not set
errno.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
Interface | Attribute | Value
|
clearerr(),
feof(),
ferror()
| Thread safety | MT-Safe
|
STANDARDS
The functions
clearerr(),
feof(),
and
ferror()
conform to C99, POSIX.1-2001, and POSIX.1-2008.
NOTES
POSIX.1-2008 specifies
that these functions shall not change the value of
errno
if
stream
is valid.
CAVEATS
Normally,
programs should read the return value of an input function,
such as
fgetc(3),
before using functions of the
feof(3)
family.
Only when the function returned the sentinel value
EOF
it makes sense to distinguish between the end of a file or an error with
feof(3)
or
ferror(3).
SEE ALSO
open(2),
fdopen(3),
fileno(3),
stdio(3),
unlocked_stdio(3)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- STANDARDS
-
- NOTES
-
- CAVEATS
-
- SEE ALSO
-
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Time: 12:21:59 GMT, April 28, 2024