Message-ID:	<34875C7D.C9FAD485@cornell.edu>
Date:	Thu, 04 Dec 1997 20:44:29 -0500
From:	"A. Sinan Unur" <sinan DOT unur AT cornell DOT edu>
Organization:	Cornell University (http://www.cornell.edu/)
MIME-Version:	1.0
To:	Nate Eldredge <eldredge AT ap DOT net>
CC:	djgpp AT delorie DOT com
Subject:	Re: Simple beginner questions
References:	<199712050124 DOT RAA26244 AT adit DOT ap DOT net>

Nate Eldredge wrote:
> 
> At 07:37  12/4/1997 -0500, Peter Palotas wrote:
> >>make a habit of setting fp to NULL after closing it. AFAIK, files do not
> >>close themselves.
> >
> >I actually think that the libc exit code does this for you, although it is
> >probably not defined in the ANSI standard that the files should be closed,
> >but DJGPP does this, I think.
> DJGPP quite definitely does it. I expect that it is part of the ANSI
> standard, since automatically closing files is guaranteed as far back 
> as K&R I. Of course, it is best to close a file when you finish with 
>it.

of course all files are closed upon program termination. that is the
required ansi behavior. the original poster was talking about not
knowing whether a given FILE* fp pointed to was open or not. there is no
way to portably do that. however, since the programmer has to take an
action to close the file, he/she can also set the pointer to NULL so
subsequent users of the pointer can check that to see if it was closed.
-- 
----------------------------------------------------------------------
A. Sinan Unur
Department of Policy Analysis and Management, College of Human Ecology,
Cornell University, Ithaca, NY 14853, USA

mailto:sinan DOT unur AT cornell DOT edu
http://www.people.cornell.edu/pages/asu1/

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