ctypes pointers

[Giorgos Giagas]

On Nov 14, 2:00 pm, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> Giorgos Giagas wrote:
> > Hi all,
> > I have started using ctypes and I am having some questions I can't
> > seem to find the answers to.
>
> > There is a structure referenced by a pointer in an other structure and
> > I want to see if it is one of the structures I have pointers to.
> > So what I think I need is a way to compare 2 pointer's memory
> > location. I can't find a way to do this. Pointer comparisons don't
> > work. Is there something else I should do?
>
> Use addressof on the contents of your pointers.

Thank you. I was looking for a pointer or structure property and
missed that.

> > The other thing is more of a curiosity... The documentation says that
> > I need to keep references to structures so they don't get freed is
> > this also true for structures returned as pointers? What about
> > structures that I cast to something else? I guess the largest of the
> > two casts gets freed like it should... can someone confirm this?
>
> The one has nothing to do with the other.
>
> If you create a struct and pass e.g. a pointer to it into a DLL, you need to
> keep a reference, otherwise the struct will be deallocated and the pointer
> is dangling.
>
> If you have a pointer and cast it to some structure, you get a structure
> object (in python) that points to a certain memory portion. But GCing that
> object doesn't do anything to the memory location.
>
That makes sence. I was confused about this thing...

Thanks a lot for the quick reply,
Giorgos