Signed word lengths and indexes

[BCS]

Hello Steven,

> On Tue, 15 Jun 2010 07:30:52 -0400, bearophile
> <bearophileHUGS at lycos.com>  wrote:
> 
>> Steven Schveighoffer:
>> 
>>> i is unsigned, and therefore can never be less than 0.  It's
>>> actually a clever way to do it that I've never thought of.
>>> 
>> Clever code is bad. It must be minimized. In some rare situations it
>> becomes useful, but its usage must be seen as a failure of the
>> programmer, that was unable to write not-clever code that does the
>> same  things.
>> 
> Clever code is bad?  What are you smoking?  In my opinion, clever code
> that is clear and concise should always be favored over code that is
> unnecessarily verbose.

Cleaver in my book normally equates to: requiters extra thought to create 
and read. The exact opposite of clever is not dumb, but simple: with very 
un-clever code the reader is I/O bound, they can understand as fast as they 
can read it. 

> 
> In this particular instance, the code is both clear and concise.

That code might be concise but it is not clear.

> 
> The following line of code should generate the exact same code, but is
> more verbose:
> 
> for(uint i = end - 1; i < length && i >= 0; --i)

That code is just as bad IMO and for exactly the same reason: you are counting 
on underflow and wrapping to make a i<j test start failing after i decrease.

> 
> The compiler will throw away the second check during optimization,
> because  i is always >= 0.  I don't see why such code should be
> preferred.
> 
> -Steve
> 
-- 
... <IXOYE><