deleting pointers with multiple references stored

Question

I create objects via new at one place in my program (let's call them actors). Those objects get passed to another object (let's call it a projectile) via their pointer. At any point that actor object can be deleted outside of projectile. delete and setting to NULL happens with this. However a pointer of it is still in projectile. I do check if != NULL but it passes those checks. The values inside the class are all bogus but the pointer itself isn't NULL.

Do I need to do a pointer to a pointer or something? I just thought if I passed a pointer around and at some point deleted and set that pointer to NULL all the other places I passed it would show NULL as well.

Some programmer dude · Accepted Answer · 2012-09-08 13:18:10Z

5

You should probably look into smart pointers, like std::shared_ptr.

answered Sep 8, 2012 at 13:18

Some programmer dude

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Matthieu M. · Accepted Answer · 2012-09-08 13:41:59Z

Have you thought about double indirection ?

Use a map of Actors: std::map<unsigned, Actor>
Only ever store the Actor ID in the projectiles

Now, supposing a monotonically increasing ID (you have about 4 billions of them available, should keep you going for a while), an ID being absent from the map means the Actor disappeared (was deleted).

pointer to a pointer is how I'll pass these objects and then check that against NULL. did a small test and it works. thanks for the suggestion though.

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