Hi,
On Mon, 1 Nov 2010, Alexander Graf wrote:
> > No. Pointers of same type which are not void pointers can be compared.
> >
> > There is even a data type ptrdiff_t, so you can also compare their
> > difference with zero.
>
> Let's ask someone who definitely knows :).
>
> Michael, is code like
>
> char *x = a, *y = b;
> if (x < y) {
> ...
> }
Pointers can be compared iff they point into the same object
(including right after the object), so it depends on what a and b were
above. This would be invalid for instance:
int o1, o2;
int *p1 = &o1, *p2 = &o2;
if (p1 < p2) ...
> valid? Or do I first have to cast x and y to unsigned longs or
> uintptr_t?
For doing a valid pointer comparison you don't have to cast anything.
Casting doesn't make an invalid comparison valid.
Ciao,
Michael.
