foef clearerr ferror函数

SYNOPSIS
       #include <stdio.h>

       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 >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE

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
       only be cleared 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 only be reset
       by the clearerr() function.

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

       For nonlocking counterparts, see unlocked_stdio(3).

ERRORS
       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.)

CONFORMING TO
       The functions clearerr(), feof(), and ferror() conform to C89 and C99.

SEE ALSO
       open(2), fdopen(3), stdio(3), unlocked_stdio(3)

COLOPHON
       This page is part of release 3.24 of the Linux man-pages project.  A description of the project, and information about reporting  bugs,  can  be  found  at
       http://www.kernel.org/doc/man-pages/.