[vox-tech] loop efficiency and testing against zero.

[Tim Riley]

Peter Jay Salzman wrote:
> I've read somewhere that a loop that runs from 0 to some number should be
> written to go in reverse order, e.g. instead of:
> 
>    for ( int i = 0;  i < 10;  ++i )
> 
> we should write:
> 
>    for ( int i = 9;  i >= 0;  --i )

I would think this:
	for( int i = MAXINT; i; --i );
is faster than this:
	for( int i = 0; i < MAXINT; ++i );

However, on my machine they both took the
same time -- 3.24 seconds.

I would think the test of 'i'
would be a single instruction and the test
of 'i < MAXINT' would take multiple
instructions. But surprise!

> 
> The rationale is that it's faster to test against 0 than some other integer,
> but it isn't obvious to me *why* it's faster.
> 
> Why is that?
> 
> Pete
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