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@(#)ferror.3 8.2 (Berkeley) 4/19/94
$FreeBSD$
.Dd January 28, 2009 .Dt FERROR 3 .Os .Sh NAME .Nm clearerr , .Nm clearerr_unlocked , .Nm feof , .Nm feof_unlocked , .Nm ferror , .Nm ferror_unlocked , .Nm fileno , .Nm fileno_unlocked .Nd check and reset stream status .Sh LIBRARY .Lb libc .Sh SYNOPSIS n stdio.h .Ft void .Fn clearerr "FILE *stream" .Ft void .Fn clearerr_unlocked "FILE *stream" .Ft int .Fn feof "FILE *stream" .Ft int .Fn feof_unlocked "FILE *stream" .Ft int .Fn ferror "FILE *stream" .Ft int .Fn ferror_unlocked "FILE *stream" .Ft int .Fn fileno "FILE *stream" .Ft int .Fn fileno_unlocked "FILE *stream" .Sh DESCRIPTION The function .Fn clearerr clears the end-of-file and error indicators for the stream pointed to by .Fa stream .
p The function .Fn feof tests the end-of-file indicator for the stream pointed to by .Fa stream , returning non-zero if it is set. The end-of-file indicator may be cleared by explicitly calling .Fn clearerr , or as a side-effect of other operations, e.g.\& .Fn fseek .
p The function .Fn ferror tests the error indicator for the stream pointed to by .Fa stream , returning non-zero if it is set.
p The function .Fn fileno examines the argument .Fa stream and returns its integer descriptor.
p The .Fn clearerr_unlocked , .Fn feof_unlocked , .Fn ferror_unlocked , and .Fn fileno_unlocked functions are equivalent to .Fn clearerr , .Fn feof , .Fn ferror , and .Fn fileno respectively, except that the caller is responsible for locking the stream with .Xr flockfile 3 before calling them. These functions may be used to avoid the overhead of locking the stream and to prevent races when multiple threads are operating on the same stream. .Sh ERRORS These functions should not fail and do not set the external variable .Va errno . .Sh SEE ALSO .Xr open 2 , .Xr fdopen 3 , .Xr flockfile 3 , .Xr stdio 3 .Sh STANDARDS The functions .Fn clearerr , .Fn feof , and .Fn ferror conform to .St -isoC .