NAME

clearerr, feof, ferror, fileno — 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);

int
fileno(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 non-zero if it is set. The end-of-file indicator can only be cleared by the function clearerr().

The function ferror() tests the error indicator for the stream pointed to by stream, returning non-zero if it is set. The error indicator can only be reset by the clearerr() function.

The function fileno() examines the argument stream and returns its integer descriptor.

ERRORS

The functions clearerr(), feof(), and ferror() should neither fail nor set the external variable errno. However, the function fileno() may fail and return -1 in case the argument stream is not associated with a valid file descriptor. (In this case the NetBSD implementation does not follow the optional POSIX recommendation to set the errno variable to EBADF.)

SEE ALSO

open(2), stdio(3)

STANDARDS

The functions clearerr(), feof(), and ferror() conform to ANSI X3.159-1989 (“ANSI C89”). The function fileno() conforms to IEEE Std 1003.1-1990 (“POSIX.1”).