C++ 数组的 auto_ptr
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auto_ptr for arrays
提问by heavyd
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.
简而言之，我想知道数组是否有类似 auto_ptr 的类型。我知道我可以推出自己的，我只是确保那里还没有什么东西。
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:
我也知道向量。但是我不认为我可以使用它们。我正在使用几个 Windows API/SDK，例如 Windows Media SDK、Direct Show API，它们是为了取回一些结构来调用一个函数，该函数需要一个指针和一个大小两次。第一次传递 NULL 作为指针以取回我必须分配的结构的大小，以便接收我正在寻找的数据。例如：
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?
由于 cbType 通常比 sizeof(WM_MEDIA_TYPE) 大，因为它有一个指向另一个结构的指针，我不能只分配 WM_MEDIA_TYPE 对象。外面有这样的东西吗？
回答by Totonga
Use
用
std::vector<BYTE> buffer(cbType);
pType = (WM_MEDIA_TYPE*)&buffer[0];
or since C++11
或自C++11
std::vector<BYTE> buffer(cbType);
pType = (WM_MEDIA_TYPE*)buffer.data();
instead.
反而。
Additional: If someone is asking if the Vectors are guaranteed to be contiguousthe answer is Yessince C++ 03 standard. There is another threadthat already discussed it.
附加：如果有人问是否保证 Vectors 是连续的，那么答案是Yes，因为 C++ 03 标准。有另一个线程已经讨论过它。
If C++11is supported by your compiler, unique_ptr can be used for arrays.
如果您的编译器支持C++11，则 unique_ptr 可用于数组。
unique_ptr<BYTE[]> buffer(new BYTE[cbType]);
pType = (WM_MEDIA_TYPE*)buffer.get();
回答by Evan Teran
boost scoped_arrayor you can use boost scoped_ptrwith a custom deleter
boostscoped_array或者您可以将 boostscoped_ptr与自定义删除器一起使用
回答by Jem
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.
当前的标准库中没有任何内容。然而，未来的标准 C++0x 有一个 unique_ptr，它取代了 auto_ptr，并且可以与数组一起使用。
A first implementation can be found here: unique_ptr
第一个实现可以在这里找到： unique_ptr
回答by Fred Larson
Not in STL. Boost has some smart pointers with a similar idea. Check out scoped_arrayand shared_array
不在 STL 中。Boost 有一些具有类似想法的智能指针。查看scoped_array和shared_array
