Mixing operations with signed and unsigned types

[Ellery Newcomer]

On 07/06/2010 07:05 PM, Stewart Gordon wrote:
> Ellery Newcomer wrote:
>> On 07/05/2010 07:59 AM, Stewart Gordon wrote:
>>> bearophile wrote:
>>>> Stewart Gordon:
>>>>> I can also imagine promoting your mindset leading to edit wars
>>>>> between developers declaring an int and then putting
>>>>> assert (qwert >= 0);
>>>>> in the class invariant, and those who see this and think it's
>>>>> brain-damaged.
>>
>> As opposed to doing what?
>
> Just using uint, of course!

For enforcing a non-negative constraint, that is brain damaged. 
Semantically, the two are very different.

int i;
assert(i >= 0);

says i can cross the 0 boundary, but it's an error if it does, i.e. 
programmer doesn't need to be perfect because it *does get caught* 
(extreme instances notwithstanding).

uint i;

says i cannot cross the 0 boundary, but it isn't an error if it does. 
programmer needs to be perfect and error doesn't get caught (unless what 
you're using it for can do appropriate bounds checking).

>
> Comparison - how do you mean?
>
> Stewart.

Mmmph. Just signed/unsigned, I guess (I was thinking foggily that 
comparison intrinsically involves subtraction or something like that)