Question about autro_ptr

Hello, I am using auto_ptr for the first time in a large project, but I have a question. How does an auto_ptr knows when to use delete[] or delete? I am using in like this:

Code:

---

auto_ptr<char> buffer(new char[buff_size]);

---

In this case, auto_ptr should delete de pointer with delete[].

What about:

Code:

---

auto_ptr<AnObject> buffer(new AnObject);

---

Thanks any insight.

From what I understand, auto_ptr stores a pointer to an object obtained via new, not new[].

Would not make it almost useless?

Quote:

---

Would not make it almost useless?

---

No, since it can still be used to perform RAII with a single object, after all.

Note that what you are trying to do by using auto_ptr with new[] can be accomplished with say:

Code:

---

std::vector<char> buffer(buff_size);

---

Well, if I am going to use a vector, using a pointer is no longer interesting, since I do not need dynamic allocation anymore. :)

Thanks for the help.

Edit: I forgot to ask. Can I really do something like:

Code:

---

vector<char> buff;

// populate vector

send(sock_fd, &buff[0], buff.size(); // send through socket connection

---

Is it really safe and portable??

Quote:

---

Is it really safe and portable??

---

As far as I know, yes, at least where &buff[0] is concerned.

The memory allocated for a vector is guaranteed to be contiguous. http://www.thescripts.com/forum/thread141366.html

So I think that if you added an extra ')', that code would work just fine. :)

Ok! Thanks!

The following from ATL could be useful:

Code:

---

CAutoVectorPtr
CAutoPtr

---

ATL is a big (and platform-specific) dependency to pull in for mere containers.

Try Boost.PtrContainer instead.

I do not know ATL, is it like Boost?
Installing Boost would not worth it, since I would only need the auto_ptr functionality.

Boost is SOOOO useful when it comes to sweet pointer objects and lots of other nifty stuff, I use it for serialization too.

I'd suggest using it as much as possible, it's one of the best libraries out there I think :)

Then I shall take a look, thank you.

In addition, for most of the boost libraries you don't even have to build it. Just download and set your include path to the boost_1_34 (or whatever it is) directory and you can use the ptr_vector.

Although in this case there's no need for the boost libraries, vector<char> is exactly what you want. The vector class does for arrays what auto_ptr does for regular pointers (auto_ptr has some weird differences, but basically this is correct).