From: "Moore, Mathew L" <MooreML@BATTELLE.ORG>
To: 'Claudio Bley' <bley@cs.uni-magdeburg.de>,
Florian Weimer <fw@deneb.enyo.de>
Cc: Joshua Nye <josh@boxcarmedia.com>, Steve Dondley <s@dondley.com>,
gcc-help@gcc.gnu.org
Subject: RE: Avoiding "assignment from incompatible pointer type" warning
Date: Mon, 21 Oct 2002 06:07:00 -0000 [thread overview]
Message-ID: <2F05A390F72A0A409390E016D23E45E8042DBEB4@ns-bco-mse4.im.battelle.org> (raw)
Certainly it is legal as far as the standard is concerned,
"A pointer to an object or incomplete type may be converted to a pointer to
a different object or incomplete type."
However, it may not be safe,
"If the resulting pointer is not correctly aligned for the pointed-to type,
the behavior is undefined."
--Matt
> -----Original Message-----
> From: Claudio Bley [mailto:bley@cs.uni-magdeburg.de]
> Sent: Monday, October 21, 2002 07:22
> To: Florian Weimer
> Cc: Joshua Nye; Steve Dondley; gcc-help@gcc.gnu.org
> Subject: Re: Avoiding "assignment from incompatible pointer type"
> warning
>
>
> >>>>> "Florian" == Florian Weimer <fw@deneb.enyo.de> writes:
>
> Florian> "Joshua Nye" <josh@boxcarmedia.com> writes:
> >>> > int *p;
> >>> > float g = 3.141592653589793238;
> >>> > p = (int *)&g;
> >>>
> >>> Is this code legal? I doubt it.
> >>>
> >> What do you consider legal and why wouldn't it be?
>
> Florian> Casting a pointer from float to int can result in
> Florian> undefined behavior on some implementations.
>
> I can't see why. Can you elaborate on that? I mean, casting on the
> machine code level does just nothing - it's just "syntactic sugar" to
> convince the compiler to be quiet. I think casting from one pointer
> type to another does no harm at all. Am I wrong?
>
> --
> Claudio Bley ASCII ribbon campaign (")
> Debian GNU/Linux advocate - against HTML email X
> http://www.cs.uni-magdeburg.de/~bley/ & vCards / \
>
next reply other threads:[~2002-10-21 13:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-21 6:07 Moore, Mathew L [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-10-21 7:04 Moore, Mathew L
2002-10-21 7:17 ` Florian Weimer
2002-10-21 7:43 ` John Love-Jensen
2002-10-13 13:37 Moore, Mathew L
2002-10-13 15:10 ` Florian Weimer
2002-10-13 9:08 Steve Dondley
2002-10-13 9:28 ` Joshua Nye
2002-10-13 9:34 ` Steve Dondley
2002-10-13 15:09 ` Florian Weimer
2002-10-13 15:19 ` Joshua Nye
2002-10-15 11:24 ` Joshua Nye
2002-10-21 3:12 ` Florian Weimer
2002-10-21 4:22 ` Claudio Bley
2002-10-21 4:30 ` Florian Weimer
2002-10-21 6:48 ` Claudio Bley
2002-10-21 4:42 ` Sebastian Huber
2002-10-21 6:43 ` John Love-Jensen
2002-10-21 6:52 ` Florian Weimer
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