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From: ark@alice.att.com (Andrew Koenig)
Newsgroups: comp.std.c++
Subject: Re: Zero-length structures and pointer comparisons
Message-ID: <23937@alice.att.com>
Date: 20 Oct 92 13:31:38 GMT
Article-I.D.: alice.23937
References: <1992Sep10.094957.23588@jyu.fi> <1992Oct16.234851.28948@microsoft.com> <23915@alice.att.com> <1992Oct19.055511.18826@jyu.fi>
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Organization: AT&T Bell Laboratories, Murray Hill NJ
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In article <1992Oct19.055511.18826@jyu.fi> sakkinen@jyu.fi (Markku Sakkinen) writes:

> In article <23915@alice.att.com> ark@alice.UUCP () writes:

> >For example, if a type T has a < operator defined that is actually a strong
> >total order relation, that makes it possible to store T objects efficiently
> >in a variety of order-based data structures such as M,N-trees, etc.

> Sorry, there is a misunderstanding here.
> The discussion in this thread (see subject line) has been about _pointer_
> comparisons all the time.  Comparison of object values is another story
> altogether.

No misunderstanding.

I made a general statement about potentially useful properties of arbitrary
types.  That statement still holds true when those types happen to be pointer
types.  That is, if < were defined as a strong total ordering on pointers,
I could use these data structures to keep track of sets of pointers.
-- 
				--Andrew Koenig
				  ark@europa.att.com