How do you access to SAFE ARRAY in a VARIANT data type returned from a COM object in C++?

Question

I am working with a COM object. I Call a function of COM objects and this functin return VARIANT data type that contain SAFE ARRAY of my equipments list. How can I work with this VARIANT to access to SAFEARRY of my equipments.

  VARIANT namList; 
  SAFEARRAY* myequip;
  namList=str->GetNames();

Answer 1

In order to use a SAFEARRAY in a VARIANT like this, you need to do a lot of validation and error-checking. Here's the rough pattern you'll need to follow. Please read the comments carefully, as I have made some assumptions about the COM API that you're using.

// verify that it's an array
if (V_ISARRAY(&namList))
{
    // get safe array
    LPSAFEARRAY pSafeArray = V_ARRAY(&namList);

    // determine the type of item in the array
    VARTYPE itemType;
    if (SUCCEEDED(SafeArrayGetVartype(pSafeArray, &itemType)))
    {
        // verify it's the type you expect
        // (The API you're using probably returns a safearray of VARIANTs,
        // so I'll use VT_VARIANT here. You should double-check this.)
        if (itemType == VT_VARIANT)
        {
            // verify that it's a one-dimensional array
            // (The API you're using probably returns a one-dimensional array.)
            if (SafeArrayGetDim(pSafeArray) == 1)
            {
                // determine the upper and lower bounds of the first dimension
                LONG lBound;
                LONG uBound;
                if (SUCCEEDED(SafeArrayGetLBound(pSafeArray, 1, &lBound)) && SUCCEEDED(SafeArrayGetUBound(pSafeArray, 1, &uBound)))
                {
                    // determine the number of items in the array
                    LONG itemCount = uBound - lBound + 1;

                    // begin accessing data
                    LPVOID pData;
                    if (SUCCEEDED(SafeArrayAccessData(pSafeArray, &pData)))
                    {
                        // here you can cast pData to an array (pointer) of the type you expect
                        // (The API you're using probably returns a safearray of VARIANTs,
                        // so I'll use VARIANT here. You should double-check this.)
                        VARIANT* pItems = (VARIANT*)pData;

                        // use the data here.

                        // end accessing data
                        SafeArrayUnaccessData(pSafeArray);
                    }
                }
            }
        }
    }
}