clearerr, feof, ferror - check and reset stream status
Contents
Attributes
For an explanation of the terms used in this section, see attributes(7).
┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
│ clearerr(), feof(), ferror() │ Thread safety │ MT-Safe │
└─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘
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).
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).
Errors
These functions should not fail and do not set errno.
History
C89, POSIX.1-2001.
Library
Standard C library (libc, -lc)
Name
clearerr, feof, ferror - check and reset stream status
Notes
POSIX.1-2008 specifies that these functions shall not change the value of errno if stream is valid.
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.
See Also
open(2), fdopen(3), fileno(3), stdio(3), unlocked_stdio(3) Linux man-pages 6.9.1 2024-05-02 ferror(3)
Standards
C11, POSIX.1-2008.
Synopsis
#include<stdio.h>voidclearerr(FILE*stream);intfeof(FILE*stream);intferror(FILE*stream);