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It must be something in the part of your code which you did not show. This works for me: C# class: <pre><code>[ComVisible(true)] [Guid("BE55747F-FEA9-4C1F-A103-32A00B162DF0")] [ClassInterface(ClassInterfaceType.AutoDual)] public class Test { //[return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_BSTR)] public string[] GetStringArray() { var a = new string[3]; a[0] = "string0"; a[1] = null; a[2] = "string2"; return a; } public string[] GetStringArray2() { return null; } } </code></pre> Calling <code>GetStringArray</code> and <code>GetStringArray2</code> from C++: <pre><code>SAFEARRAY* pSA = NULL; testObject->GetStringArray(&pSA); printf("str0: %ls\n", ((BSTR*)(pSA->pvData))[0]); printf("ptr1: %x\n", ((BSTR*)(pSA->pvData))[1]); printf("str2: %ls\n", ((BSTR*)(pSA->pvData))[2]); SAFEARRAY* pSA2 = NULL; testObject->GetStringArray2(&pSA2); printf("pSA2: %x\n", pSA2); </code></pre> Run: <pre><code>str0: string0 ptr1: 0 str2: string2 pSA2: 0 </code></pre> I did not have to specify how to marshal the array (the commented out line), because it gets marshaled as <code>SAFEARRAY(VT_BSTR)</code> by default. EDITED: I guess I see where the problem is. You're using ATL <code>CComSafeArray</code> which doesn't expect a <code>NULL</code> SAFEARRAY by design: <pre><code>CComSafeArray(_In_ const SAFEARRAY *psaSrc) : m_psa(NULL) { ATLASSERT(psaSrc != NULL); HRESULT hRes = CopyFrom(psaSrc); if (FAILED(hRes)) AtlThrow(hRes); } </code></pre> You should change your code like this: <pre><code>CComSafeArray<BSTR> itemEntities; SAFEARRAY* pItemEntities = objController1->ListItems(sPath); if (NULL != pItemEntities) itemEntities.Attach(pItemEntities); </code></pre> Or, assign <code>m_psa</code> directly: <pre><code>CComSafeArray<BSTR> itemEntities itemEntities.m_psa = objController1->ListItems(sPath); if (!itemEntities) { // NULL returned } </code></pre>
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1. COThis worked for meCComSafeArray<BSTR> itemEntities; SAFEARRAY* pItemEntities = objController1->ListItems(sPath); if (NULL != pItemEntities) itemEntities.Attach(pItemEntities);
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