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POPassing a CComSafeArray across a COM boundary
 

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  1. POPassing a CComSafeArray across a COM boundary
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    <p>I'm trying to (i) get a safearray of longs across a COM boundary and (ii) use CComSafeArray for convenience.</p> <p>My problem is that I'm getting unpredictable crashes after setting the COM property (see <strong>pPrologue->EligibleProducts = var;</strong> below). I've found it very hard to understand how to use CComSafeArray from the Microsoft documentation, can anyone shed any light? Thank you in advance!</p> <p>In the IDL I have:</p> <pre><code>[propget, id(1), helpstring("property EligibleProducts")] HRESULT EligibleProducts([out, retval] VARIANT* pVal); [propput, id(1), helpstring("property EligibleProducts")] HRESULT EligibleProducts([in] VARIANT newVal); </code></pre> <p>My server code is:</p> <pre><code>STDMETHODIMP CPrologue::put_EligibleProducts(VARIANT newVal) { HRESULT hr = E_FAIL; AFX_MANAGE_STATE(AfxGetStaticModuleState()) //start by clearing out any existing data m_EligibleProducts.clear(); if(newVal.vt | (VT_ARRAY &amp; VT_I4)) { //construct a wrapper class with the passed in SAFEARRAY CComSafeArray&lt;long&gt; wrapper; wrapper.Attach(newVal.parray); int iProductID = 0; //loop through products and add them to our vector int iCount = wrapper.GetCount(); for(int iIndex = 0; iIndex &lt; iCount; iIndex++) { iProductID = wrapper.GetAt(iIndex); if(iProductID &gt; 0) { m_EligibleProducts.push_back(iProductID); } } hr = S_OK; return hr; } </code></pre> <p>And my calling code is:</p> <pre><code> VARIANT var; ::VariantInit(&amp;var); var.vt = VT_ARRAY | VT_I4; CComSafeArray&lt;long&gt; wrapper; for(std::vector&lt;long&gt;::const_iterator it = products.begin(); it != products.end(); it++) { wrapper.Add(*it); } //get the SAFEARRAY from the wrapper var.parray = wrapper.Detach(); //and store it on the appropriate business object IProloguePtr pPrologue = pCustomer-&gt;Prologue; **pPrologue-&gt;EligibleProducts = var;** //clean up the variant (and hence SAFEARRAY) ::VariantClear(&amp;var); </code></pre>
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