How can I determine if a C++ object has been deallocated?

Question

I have a previous question that was answered in which I describe difficulties catching an exception when I try to access an object that has been deallocated by a third-party

Answer 1

You can't. If the function you're using doesn't give you ways of knowing whether or not it deallocated the object itself, there's no way you can find out.

Edit: Well, unless the object in question is an instance of your own class and you can modify the destructor like Adrian suggested.