Re: Please don't do this (code fragment)

[elf@florence.buici.com]

Thanks.  This makes sense.

On Tue, Jan 15, 2002 at 07:25:29PM +0100, Olaf Weber wrote:
> Thomas Bushnell writes:
> 
> > Actually, the C standard does essentially guarantee two's complement
> > arithmetic.  It specifies integer overflow behavior and
> > signed/unsigned conversion behavior exactly.
> 
> It does for unsigned integers, but for signed integers overflow is
> undefined behaviour.  The clearest statement of that is 3.4.3, albeit
> in an example:
> 
>    3.4.3
>  1 undefined behavior behavior, upon use of a nonportable or erroneous
>    program construct or of erroneous data, for which this International
>    Standard imposes no requirements
>  2 NOTE Possible undefined behavior ranges from ignoring the situation
>    completely with unpredictable results, to behaving during translation
>    or program execution in a documented manner characteristic of the
>    environment (with or without the issuance of a diagnostic message),
>    to terminating a translation or execution (with the issuance of a
>    diagnostic message). 
>  3 EXAMPLE An example of undefined behavior is the behavior on integer
>    overflow.
> 
> -- 
> Olaf Weber
> 
>                (This space left blank for technical reasons.)
> 
> 
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