> > 1. Line 51 of test085.cxx, I had to change from:
> >
> > for (ITER arg = --patend; i > 0; --arg, --i)
> > {
> > ...
> > }
> >
> > to:
> >
> > for (ITER arg = patend; i > 0; --i)
> > {
> > --arg;
> > ...
> > }
>
> Why is that? There shouldn't be any problem here--if there is nothing
> valid before patend then I'd expect the loop condition (i > 0) to fail
> right away, and the decrement would never be executed. I'll make the
> change if that helps, but what's the error message here exactly?
Consider the case that patend is begin() and i=0, i>0 fails but not until arg =
--patend is executed.
Or say initial condition is i=0, patend is begin()+1, arg will be initialized
to begin(), after first iteration, the loop will try to execute --arg, --i
which is also not allowed in VC++8.
>
>
> > 2. Line 69 of test083.cxx need to be changed from:
> >
> > for (result::const_iterator r = R.begin(); r != R.end(); --i, ++r)
> > ...
> >
> > to:
> >
> > ++i;
> > for (result::const_iterator r = R.begin(); r != R.end(); ++r) {
> > ...
> > }
>
> That's a very radical change to the loop. Are you sure there isn't some
> mistake here? That should probably make the test fail because it will
> make the test look at different data.
Sorry, there should be a --i inside the for loop. The reason for the change is
the same as the first case, i.e. in the original code, --i and ++r must be
executed together but r is allow to go past the last item whilst i is not allow
to decrement past the first element.
>
> > Both changes are needed to prevent a (forward) iterator from decrementing
> > past the first element.
>
> There must be some confusion here... If they were forward iterators, then
> they shouldn't be able to decrement at all! There should be a
> compile-time error for that. And I think (perhaps wrongly--it's not
> unheard of) that in the case of test085.cxx it's not possible for the
> "--patend" to go below the beginning of the sequence. Even if it can,
> doing the initial "--arg" instead should have the exact same problem!
>
I use the word (forward) to describe iterator(s) to make a contrast with
reverse_iterator(s), which are allowed to move one element past the begining of
a collection.
Cheers!
Xiaofeng
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