FERROR(3) Linux Programmers Manual FERROR(3)
clearerr, feof, ferror, fileno - check and reset stream status
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 || _XOPEN_SOURCE
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
For non-locking counterparts, see unlocked_stdio(3).
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.)
The functions clearerr(), feof(), and ferror() conform to C89 and C99.
open(2), fdopen(3), stdio(3), unlocked_stdio(3)
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