Re: pointer casting

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#2635

From: Dan Pop
Date: Sun, 21 Apr 1996 17:11

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In <4lbao2$lkd@solutions.solon.com> Network News <news@dcs.warwick.ac.uk> writes:

>Are conversions of pointers without the proper alignment actually
>illegal, i.e. invoking undefined behaviour?

All arbitrary pointer conversions are illegal, unless the standard 
explicitly states otherwise.  The result of such a conversion is
undefined behaviour, indeed.

>It seems to me that an
>implementation where conversion of an unaligned byte pointer to a word
>pointer will trap ought to be conforming.

On most real world platforms, the trap occurs when the resulting pointer
is dereferenced.  But an implementation where the trap occurs at 
conversion time would be conforming (when it comes to undefined behaviour,
any behaviour is conforming).

Dan
--
Dan Pop
CERN, CN Division
Email: danpop@mail.cern.ch 
Mail:  CERN - PPE, Bat. 31 R-004, CH-1211 Geneve 23, Switzerland

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From: danpop@mail.cern.ch (Dan Pop)
Newsgroups: comp.lang.c.moderated
Subject: Re: pointer casting
Date: 21 Apr 1996 12:11:01 -0500
Organization: CERN European Lab for Particle Physics
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