CComSafeArray use

Question

I have a Com function:

GetData (SAFEARRAY ** pRetVal)

I have the following piece of code:

SAFEARRAY *ppData = NULL;       
hr = pmyInterface->GetData( &ppData );
CComSafeArray<IUnknown*> pSafeArgs;
pSafeArgs.Attach( ppData );

I have to change it, and remove ppData, and also remove the Attach command.

It should be something like this:

CComSafeArray<IUnknown*> pSafeArgs;
hr = pmyInterface->GetData( ((SAFEARRAY**)&pSafeArgs )))

But this doesn't work. Probably a problem with the release of the CComArray.

How can I do it?

Answer 1

Usually when creating the CComSafeArray you would specify the type of data that will be held within it, eg:

CComSafeArray<char> pSafeArgs;

To supply this to your COM function you would do the following:

HRESULT hr = pmyInterface->GetData((LPSAFEARRAY)pSafeArgs);

Answer 2

Try using CComSafeArray::GetSafeArrayPtr():

// Substitute T with the actual type of items 
// in your SAFEARRAY, e.g. CComSafeArray<BYTE>
CComSafeArray<T> safeArgs;

hr = pmyInterface->GetData( safeArgs.GetSafeArrayPtr() );

(In general, you should avoid C-style casts in C++ code.)