I've read all the books, gotten the t-shirt and everything, and I still don't quite get it. Especially about pointer arrays. Here's a hypothetical example:

class Object {
   void DoSomething();
};

void Object::DoSomething() {
   // whatever
}

int main() {
   Object** list; // an array of pointers to Objects

   list = new Object*[num_objects];

   for(int i = 0; i < num_objects; i++) {
      InitObject(&(list));
   }

   list[random_number]->DoSomething();
}

Suppose hypothetically that it crashes when I call DoSomething(). I'm probably doing something embarassingly wrong; please enlighten me!

Thanks a bunch! Except, what happens if "Object" is abstract and you can't create instances of it?

What does InitObject() do? Does it actually create (as in use new to create) instances of objects that inherit from Object? If so, then you should supposedly be fine. Because it looks like InitObject() takes the address of a pointer, that means that InitObject() can actually change the value of the pointer, which would be necessary if it were using new to create new instances.

However, if InitObject() is only meant to take an already existing instance of an object, and set some values in it and such, then you have a problem. When you new the array, what you get is an array of pointers, but all the pointers are random, just like any uninitialized variable. Until you actually create some objects, or point to objects that have already been created, you won't be able to use those pointers for anything, or else you'll get memory access violation errors.

One possibility is that InitObject() is attempting to create objects, but sometimes it doesn't, and it might possibly set the pointer to NULL. Accessing a NULL pointer with your DoSomething() call will also cause a memory access violation error. Maybe you should be checking your pointer, to make sure it isn't NULL, before you call DoSomething().

Thanks for the tips, snk_kid. I know how std::vector works, I just hadn't thought to use it in this scenario.

I'm gonna have to stop being hypothetical.

"Object" is an abstract, non-instantiable direct3d object. Init_Object() is a D3D function that allocates and sets the object. This may clear a few things up for you. :)

Thanks for the replies! I'll try out your ideas.

Okay, I tried using an std::vector, and it still doesn't work:

for(int i = 0; i < num_objects; i++) {   Object* object;   Init_Object(&object);   list.push_back(object);}list->DoSomething(); // crashes