Get a pointer instead of a reference from a boost::ptr_vector

Question

I recently found the boost ptr_vector useful to manage my collection of heap-allocated objects. The pointer collection library is very nice, but unfortunately, I'm being held up by one thing.

Another part of my code needs to explicitly hold a pointer to one of my objects in the ptr_vector (for specific reasons it cannot be a reference). However, when you access an object in a ptr_vector, you get a reference, T& (even though you used ptr_vector.push_back(T *)

Is there anyway I can get a plain pointer out of a boost::ptr_vector?

Can you explain why it must be a pointer? Maybe there is an alternative. — Björn Pollex, Jan 17 '12 at 09:35
Can you also explain what you mean by *hold*: does it imply ownership ? Or merely to access the pointed value ? — Matthieu M., Jan 17 '12 at 10:56

score 9 · Accepted Answer · answered Jan 17 '12 at 09:32

9

Yes,

boost::ptr_vector<int> v;
v.push_back(new int());
int* ptr = &v[0];

answered Jan 17 '12 at 09:32

ronag

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Steve Jessop · Answer 2 · 2012-01-17T10:17:00.243

3

Same way you do from a regular vector: &myvec[index]. Of course you're on your own ensuring that the pointer is not used after the object is no longer there. If this becomes difficult then you can consider switching to a vector<shared_ptr<T> > rather than a ptr_vector<T>.

edited Jan 17 '12 at 10:17

answered Jan 17 '12 at 09:33

Steve Jessop

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Get a pointer instead of a reference from a boost::ptr_vector

2 Answers2