C++ auto_ptr for arrays

Question

In short, I am wondering if there is an auto_ptr like type for arrays. I know I could roll my own, I'm just making sure that there isn't already something out there.

I know about vectors as well. however I don't think I can use them. I am using several of the Windows APIs/SDKs such as the Windows Media SDK, Direct Show API which in order to get back some structures to call a function which takes a pointer and a size twice. The first time passing NULL as the pointer to get back the size of the structure that I have to allocated in order to receive the data I am looking for. For example:

CComQIPtr<IWMMediaProps> pProps(m_pStreamConfig);
DWORD cbType = 0;
WM_MEDIA_TYPE *pType = NULL;

hr = pProps->GetMediaType(NULL, &cbType);
CHECK_HR(hr);

pType = (WM_MEDIA_TYPE*)new BYTE[cbType];   // Would like to use auto_ptr instread
hr = pProps->GetMediaType(pType, &cbType);
CHECK_HR(hr);

// ... do some stuff

delete[] pType;

Since cbType typically comes back bigger than sizeof(WM_MEDIA_TYPE) due to the fact is has a pointer to another structure in it, I can't just allocate WM_MEDIA_TYPE objects. Is there anything like this out there?

Answer 1

boost scoped_array or you can use boost scoped_ptr with a custom deleter

Answer 2

Not in STL. Boost has some smart pointers with a similar idea. Check out scoped_array and shared_array

Answer 3

Use

std::vector<BYTE> vector(cbType);
pType = (WM_MEDIA_TYPE*)&vector[0];

instead.

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Additional: If someone is asking if the Vectors are guaranteed to be contiguous the answer is Yes since C++ 03 standard. There is another thread that already discussed it.

Answer 4

There is nothing for this in the current std library. However, the future standard C++0x has an unique_ptr, which comes in replacement of auto_ptr, and which works with arrays.

A first implementation can be found here: unique_ptr