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From: willcr@bud.sos.ivy.isc.com (Will Crowder)
Newsgroups: comp.lang.c
Subject: Re: Variable structure size -- ANSI ?
Message-ID: <1991Apr12.234258.23800@ism.isc.com>
Date: 12 Apr 91 23:42:58 GMT
References: <8334@umd5.umd.edu> <3111@kluge.fiu.edu> <4204@rwthinf.UUCP> <6246@male.EBay.Sun.COM>
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In article <6246@male.EBay.Sun.COM>, harry@matilda.uk.sun.com (Harry
Protoolis - Sun EHQ) writes:

> |> Michael N Johnston writes:
> |> ]>struct foo {
> |> ]>unsigned short recsize;
> |> ]>unsigned short num;
> |> ]>char info [24];
> |> ]>byte flags;
> |> ]>char filename[1]
> |> ]>};
> |> ]>Where, foo.filename is a placeholder for a variable length string.
> |> 
> 
> A question really, does the standard *guarantee* the physical order of
> structure elements ? I looked in K&R 2 and couldn't find anything.

The ANSI standard guarantees that elements of a structure will be allocated
in the order declared.  However, there may be any amount of padding between
structure elements.  But yes, for

	struct foo {
		int a;
		int b;
	};

&foo.b is guaranteed to be greater then &foo.a.  Also, &foo is guaranteed
to be equal to &foo.a.

|> Harry
|> --- 

Hope this helps,

Will

--------------------------------------------------------------------------------
Will Crowder, MTS            | "An optimist sees a glass that's half full.  A
(willcr@ivy.isc.com)         |  pessimist sees a glass that's half empty.  An
INTERACTIVE Systems Corp.    |	engineer sees a glass that's twice as big as
			     |  it needs to be!"  -- unknown (at least, by me)