Re: fun with ?:

[Derek M Jones <derek@knosof.co.uk>]

Al,

>> cast of float bit painful in recursive descent parsers.  I've managed
>> to find cases where Comeau's online compiler doesn't get it right,
>> and they're pretty good.

I would be interested to know what these cases were.

> extern int n;
> struct {
> 	int x : 1 + n - n;
> } y;
> 
> passes with -pedantic -std=c99.  Replacing that with 1 + n - n + n - n
> is still OK with gcc; 1 + n + n - n - n is not.
> 
> So that's hardly an example of, well, anything.

It is an example of order of evaluation mattering when overflow
occurs.

What with game programming growing and growing in importance
I think it won't be long before saturated interger arithmetic
overflow will be encountered just as often as the 'conventional'
wrapping behavior.

-- 
Derek M. Jones                              tel: +44 (0) 1252 520 667
Knowledge Software Ltd                      mailto:derek@knosof.co.uk
Applications Standards Conformance Testing    http://www.knosof.co.uk