Careful "for" Loops

[Stan Brown]

In article <1991Mar21.181807.24059 at ism.isc.com>, willcr at bud.sos.ivy.isc.com (Will Crowder) writes:
> On a somewhat related note, the ANSI C standard guarantees that the address of
> the element one past the end of an array is representable and won't overflow.
> This makes loops like
> 
> {
> 	int a[10];
> 	int *p, *q;
> 
> 	/* point q and at end a */
> 
> 	q = &a[sizeof a / sizeof a[0]];
> 
> 	for (p = a; p != q; p++)
> 		useful_work_goes_here();
> }
> 
> work properly.  [The (sizeof a / sizeof a[0]) expression keeps the explicit 
> knowledge of the size of the array in its declaration.]  The implementation
> must place the array a such that &a[10] is representable and will not
> overflow.

I use
        for (p=a; p<a; p++)
Then if my loop also increments p, the loop still terminates.

(Yes, I know my loop _shouldn't_ increment p, but sometimes I
make coding errors.)

My opinions are mine:  I don't speak for any other person or company.
                   email (until 91/4/30): browns at iccgcc.decnet.ab.com
Stan Brown, Oak Road Systems, Cleveland, Ohio, USA    +1 216 371 0043