Question

I’m writing some code in MFC and I want to use auto pointers. I’ve come across two different classes that look like they do the same thing: CAutoPtr and std::auto_ptr What are people’s thoughts about the two different implementations?

Further, I know there is std::tr1::shared_ptr. Is there a similar shared_ptr that is in ATL/MFC?

Answer 1

Both CAutoPtr and auto_ptr give you smart pointer semantics including transfer of ownership semantics. CAutoPtr is an ATL class — built using COM. It is a non-standard extension for a particular OS. auto_ptr on the other hand is standard C++. If you want to use a container of such objects you have to use CAutoPtrArray or CAutoPtrList.

An important point to note is that there is something called auto_ptr_ref that allows you to return auto_ptrs as a return value. There is no such thing with CAutoPtr.

auto_ptr is deprecated in C++0x. Use unique_ptr if you have to: you can use them in move-aware containers and also get some safety from unsafe implicit moves of l-values.