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Path: utzoo!mnetor!uunet!nuchat!steve
From: steve@nuchat.UUCP (Steve Nuchia)
Newsgroups: comp.lang.c
Subject: Re: FILE * <-> System File Handles
Message-ID: <366@nuchat.UUCP>
Date: Sun, 4-Oct-87 21:04:48 EDT
Article-I.D.: nuchat.366
Posted: Sun Oct  4 21:04:48 1987
Date-Received: Wed, 7-Oct-87 07:01:24 EDT
References: <2.bagpiper@oxy.uucp>
Organization: Public Access - Houston, Tx
Lines: 48
Summary: I don't know how to phrase this gently

In article <2.bagpiper@oxy.uucp>,  writes:
> ahhhh...I had a problem the other day the I think may have something to do
> with this.  The following piece of code will clarify:
> 
> #include <stdio.h>
> main()
> {
>  FILE *otherptr ;
> 
>  fprintf(stdprn,"This goes to the system printer!!") ;
>  otherptr = strprn ;
>  fprintf(otherptr,"And so does this...(on the same line even)\n") ;
>  fclose(otherptr) ;
>  fprintf(stdprn,"But this doesn't....???????\n") ;
> }

It suprises you that stdprn is closed after you close it?  What
exactly do you expect that program to do?  Lets look at it.

You have a local variable of type FILE *.  You assign the value
stdprn to it.  Then you pass that value (ie, stdprn) to fclose.
Now, what would you expect to happen if you had said:

	fclose ( stdout );
	fprintf ( stdout, "help, I can't talk anymore!\n" );

I would expect it to not be able to talk and thus it would say nothing.

Now, recalling that this is C and not some hypothetical language we
are discussing, how is fclose supposed to know the difference between

	fclose ( stdprn );

and

	foo = stdprn;
	fclose ( foo );

?????????

***** SPOILER WARNING *****

It isn't.

-- 
Steve Nuchia	    | [...] but the machine would probably be allowed no mercy.
uunet!nuchat!steve  | In other words then, if a machine is expected to be
(713) 334 6720	    | infallible, it cannot be intelligent.  - Alan Turing, 1947