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From: breck@aimt.UUCP (Robert Breckinridge Beatie)
Newsgroups: comp.lang.c
Subject: Re: Arrays of Unknown Length in Structures (and sizeof)
Message-ID: <95@aimt.UUCP>
Date: Wed, 30-Sep-87 01:10:25 EDT
Article-I.D.: aimt.95
Posted: Wed Sep 30 01:10:25 1987
Date-Received: Sat, 3-Oct-87 07:48:31 EDT
References: <243@mit-prep.ARPA> <1044@ius1.cs.cmu.edu>
Organization: AIM Technology, Palo Alto, CA
Lines: 38
Summary: Possibly another reason that it's not "kosher"

In article <1044@ius1.cs.cmu.edu>, edw@ius1.cs.cmu.edu (Eddie Wyatt) writes:
> > 	struct  STRUCT_FOO
> > 	{
> > 	  int  one;
> > 	  int  two;
> > 	  int  open[];
> > 	};
> > 
> > 	  foo_p = malloc(sizeof (struct STRUCT_FOO) + (7 * sizeof (int)));
> > 
> > 	  for (i = 0; i < 7; ++i)
> > 	   foo_p->open[i] = i * 100;
> > 
> .......
> > As far as I'm concerned, if this isn't kosher, it should be!
> 
>    Let me give you a reason of why this should not be "kosher".
> 
[ Reason deleted for brevity ]

Here's another possible reason (corrections welcome) that this isn't "kosher".
If the space for the array is allocated in the structure itself, then this
makes the size of the structure undefined (I think).  What would the compiler
do for an array of STRUCT_FOO?  What would be the address of bar[10] when
bar is an array of STRUCT_FOO?

This "feature" is interesting but I don't think it's interesting enough to
give up the ability to declare arrays of structures.  Also, what would a
compiler do if the structure includes more than one field of unknown size?
This seems a potentially nightmarish situation.

Now since the original article stated that "both [compilers] do what I want"
it seems that I may be making a fool of myself again.  Have I missed something
obvious?  What is really going on here?

-- 
Breck Beatie
uunet!aimt!breck