auto_ptr vs shared_ptr

[Markus Dehmann]

The main difference between std::auto_ptr and boost::shared_ptr is that
auto_ptr has the transfer-of-ownership semantic. That makes it impossible
to store auto_ptrs in STL containers because the containers use the copy
constructor when you store or get an element.

So, is it recommended to use shared_ptr instead? Are there any
disadvantages of shared_ptr? Is shared_ptr slower maybe?

It seems for shared_ptr you only need the boost headers, not the libraries.
Is that true?

Thanks!

 

[Pete Becker]

So, is it recommended to use shared_ptr instead? Are there any
disadvantages of shared_ptr? Is shared_ptr slower maybe?

shared_ptr allocates a control block from the heap.

It seems for shared_ptr you only need the boost headers, not the libraries.
Is that true?

Ask on the boost reflector.

 

[Rapscallion]

So, is it recommended to use shared_ptr instead? Are there any
disadvantages of shared_ptr? Is shared_ptr slower maybe?

Better don't waste your precious time and join the International Smart
Pointer Haters Club, an ever growing conglomerate of people who think
that smart pointers are not at all a smart idea. See e.g.
http://groups-beta.google.com/group..._frm/thread/3ec52fd6f9d370c0/8a6742e2b0036832

 

[msalters]

Markus Dehmann schreef:

The main difference between std::auto_ptr and boost::shared_ptr is that
auto_ptr has the transfer-of-ownership semantic. That makes it impossible
to store auto_ptrs in STL containers because the containers use the copy
constructor when you store or get an element.

So, is it recommended to use shared_ptr instead? Are there any
disadvantages of shared_ptr? Is shared_ptr slower maybe?

Disadvantages? Sure, the share count had to be stored somewhere.
sizeof(auto_ptr<T>)==sizeof(T*) on many systems. Furthermore, this
may decrease the cache efficiency.

Furthermore, if the semantics you need /are/ transfer of ownership
(source/sink functions) then std::auto_ptr makes it clear what happens.

It seems for shared_ptr you only need the boost headers, not the libraries.
Is that true?

AFAIK, yes, but that's technically off-topic (and it could change).

Regards,
Michiel Salters