A tutorial I have on website explaining how to use the auto_ptr template in c++.

The url is Auto_ptr Tutorial

P.S. I wrote this a while back, it is a very good. I'd love feedback on it.

Looks good, but std::auto_ptr<> is declared in <memory> and std::endl is only guaranteed to be declared in <ostream> i.e. <iostream> probably will declare it, but it's not guaranteed by the C++ standard.

Also, your last example uses a class that is dangerous to copy. I'd recommend either declaring but not implementing a private copy-constructor and copy-assignment operator, or implementing public versions of each that make deep copies (but be careful with polymorphic base classes!). As an extension to your article, have a look at std::tr1::shared_ptr aka boost::shared_ptr and boost::weak_ptr. They're even more useful than auto_ptr! And using a shared_ptr instead of auto_ptr in your last example will automagically make it safe to copy.

For a similar hand-coded shared pointer implementation have a look at mine: http://www.nunswithguns.net/guff/core/ptr.h and shared.h for core::ptr and core::array and their base class which provides reference-counted auto-destroy sematics for any class. An example using FILE* is given, which is fclose()d automatically when the last copy goes out of scope.

I plan on changing them to remove the exception specifications and to use the protected destructor idiom. In fact I'll write that on the back of my hand to do tonight!!

Also, if you're feeling really adventurous, check out Andrei Alexandrescu's policy-based smart-pointer in "Modern C++ design".

Edd

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Ahhh I see.

I've heard of the other smart pointers but I never got around to actually using one of the alternates. I made the tutorial on the auto pointer in the c++ standard simply because it is the most bare bones and standard. I heard good things about the ones in boost though. I hear they can delete arrays of memory amongst other things.

Btw, thanks for telling me about the std::endl. Thats really interesting.

:::raises eyebrows:::
"yes.....now I see...."

Well boost::shared_ptr is now standard in the std::tr1 namespace if your library supports it. It will probably end up as std::shared_ptr when the next revision comes around. It can be made using standard C++ constructs anyway (as can/does the ptr.h file I mentioned). Just food for thought!

By the way, if anyone is serious about C++ and doesn't know what auto_ptr is or does, give MalachiX's article a read. auto_ptr is sorely underused given that it provides so many benefits when writing resource-managed and exception safe code.

Edd