Returning string array From COM - ATL

1)     In IDL file add method with argument SAFEARRAY(BSTR)* retval method. 2)     Add methods in .h and .cpp file .( with argument type SAFEARRAY** )

Example: Suppose in Visual studio we added a ATL simple object with name ComTestObject then    wizard  will create ComTestObject.h, ComTestObject.cpp file and a new interface IComTestObject in ild    file will generate.         Adde following Code to return array of string :

·         Edit IDL file interface IComTestObject : IDispatch{                   [id(1), helpstring("method GetValutArray")] HRESULT GetValutArray([out,retval] SAFEARRAY(BSTR)* pValutarr); };

·         ComTestObject.h #include "atlsafe.h" class ATL_NO_VTABLE CComTestObject :.. {       //{wizard generated code}       public:             STDMETHOD(GetValutArray)(/*[in,out]*/ SAFEARRAY** pValutarr);       private:             CComSafeArray<BSTR> m_ValutArray; }

·         ComTestObject.cpp STDMETHODIMP CComTestObject::GetValutArray(SAFEARRAY** pLarr) {       HRESULT lResult = S_OK; // return code for OLE functions       ULONG ulCount = 2;//The number of elements in the array       LONG lLBound  = 0;//The lower bound value; that is,                         //the index of the first element in the array.      lResult = m_ValutArray.Create(ulCount,lLBound);       if(  S_OK == lResult)       {             m_ValutArray.SetAt(0,_T("Sen"));             m_ValutArray.SetAt(1,_T("API"));             *pLarr = m_ValutArray;       }       return lResult; }

Consuming COM in C#. Add COM refetence and add following code.

public string[] GetVaultArray()         {             Array vaultArray = null;             try             {                 CTsetClass testObj = new CTsetClass();                 vaultArray = testObj.GetValutArray();             }             catch (COMException)             {                 //Handle Exception             }             try             {                 string[] vaultStringarray = (string[])vaultArray;                 return vaultStringarray;             }             catch (InvalidCastException)             {                 //Handle Exception             }             return null;         }

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