Setting a iterator's object to NULL

I created some test code to debug one of my problems, and I think I narrowed it down. One list has shared pointers, the other has addresses of the object pointed to by the shared pointer. When the shared pointer is deleted, it doesn't set the object to NULL so the list full of addresses has some bogus value. Here's some code to explain:

Code:

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        list<shared_ptr<Enemy>> elist;
        list<shared_ptr<Enemy>>::iterator it;
        Enemy* ep;

        {
                shared_ptr<Enemy> e(new Enemy);
                elist.push_back(e);
                ep=e.get();
        }
       
        it=elist.begin();
        //THIS DOES NOT WORK, but indicates what I want: (*it)=NULL;
        elist.erase(elist.begin());
        //this fails
        assert(ep);

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How can I assign a new value to what an iterator is pointing to, or otherwise fix this?

it->reset()

But erasing should be enough. The destructor takes care of deleting the object.

Quote:

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Code:

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        //this fails
        assert(ep);

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No, it won't. ep is a dangling but non-null pointer.

I'll give reset a shot when I get home, but yes, that assertion does fail (with the code I have posted now).

Quote:

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Originally Posted by CornedBee

No, it won't. ep is a dangling but non-null pointer.

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QFT!

"This fails" or this "fails to fail"? :)

I guess I said that wrong. I WANT ep to be a NULL pointer, or somehow be able to tell when whatever ep is pointing to has been deleted.

Just a guess, but wouldn't making ep a weak_ptr do help with that?

Quote:

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Originally Posted by Daved

Just a guess, but wouldn't making ep a weak_ptr do help with that?

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Thanks a ton. That was exactly what I needed.