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

       C11, POSIX.1-2008.

HISTORY

       C89, POSIX.1-2001.

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)