Re: [OFFTOPIC] Re: A bit off-topic ... (fwd)

Arvind Sankar (arvinds@mit.edu)
Wed, 31 Mar 1999 20:06:56 -0500


On Thu, Apr 01, 1999 at 08:42:01AM +0800, David Luyer wrote:
> Try this one -
>
> main() {
> int x=0, y=0, z = 0;
>
> x ? y : z = 1;
>
> printf("%d %d %d\n", x, y, z);
> }
>
> Compiles fine. Output: 0 0 1.
> Now set x=1 and find output: 1 1 0.
> Isn't that sick :-) gcc 2.7.2.3.

what's sick about it? it's a documented gcc extension.

>
> Based on that, a really good compiler could give your above statement as
>
> x = (x=1) = 2

this is illegal. First, (x=1) is not an lvalue, secondly even if it were,
the assignment would be undefined.

>
> and then come out with x = 2.

or mke2fs /dev/{h,s}da just to teach you a lesson :)

-- arvind

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