[Info-vax] decrementing & for loops in C

[Bob Eager]

On Thu, 8 Jan 2009 16:01:13 UTC, billg999 at cs.uofs.edu (Bill Gunshannon) 
wrote:

> In article <6sml69F71m8lU1 at mid.individual.net>,
> 	billg999 at cs.uofs.edu (Bill Gunshannon) writes:
> >
> >                                Maybe I will try some of the compilers I
> > have to see if one of them actually does it.
> 
> OK, I tried it with GCC on x86.  I tried using both "=" and "=="
> with and without the "-O" option.
> 
> Results:
> 
> == & no optimization:  Loop is there but condition to execute loop never
>                        exists.
> 
> = & no optimization:   Loop code not even generated.
> 
> == & "-O":  Loop code including loop setup optimized out of code.
> 
> = & "-O":  Loop code including loop setup optimized out of code.
> 
> So, GCC at least can tell the logic does not allow for execution of the
> loop and takes the appropriate action.  Sadly, it does not contain code
> the cause the computer to reach out and slap the programmer on the back
> of the head.

Try using:      gcc -Wparentheses ...

-- 
Bob Eager