Is it safe to return vector>?

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Why is it wrong to use std::auto_ptr<> with standard containers?

I have a function to return some Object in pointer, so I use:

vector <auto_ptr <Object> > func() { ... }

I want to know whether it is safe or not?

This is not a good idea - see [here](http://stackoverflow.com/a/2643757/160206). — Björn Pollex, Oct 11 '12 at 08:48
You should use std::unique_ptr. Use boost's one if you can't use C++11. — akappa, Oct 11 '12 at 08:49
It is not safe to use `vector`s of `auto_ptr`, so returning one cannot be safe either. See [here](http://www.gotw.ca/publications/using_auto_ptr_effectively.htm). — juanchopanza, Oct 11 '12 at 08:49
See [Why is it wrong to use std::auto_ptr with standard containers?](http://stackoverflow.com/questions/111478/why-is-it-wrong-to-use-stdauto-ptr-with-standard-containers?rq=1) — Bo Persson, Oct 11 '12 at 09:14

score 0 · Answer 1 · answered Oct 11 '12 at 08:57

stl likes to copy elements around and use temporary copies in its algorithms (e.i. they have to be "copy-constructible" and "assignable"). While this is not true for auto_ptr. Assigning one auto_ptr to another transfers ownership of the pointer.

auto_ptr<foo> A = B; B becomes NULL, A is the new owner of the pointer and B is unusable. And when the temporary object takes ownership it does not return it and you have vector of dangling pointer or NULL pointers instead.

You can use c++11 smart pointer, or boost smart pointers or implement one yourself.

Is it safe to return vector>?

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