Passing string Array from unmanaged to managed code.

[Elena Kr]

Hi, I have task I believe many people implemented many times.
The C++ application has to pass array of string to C# dll. To my surprise I have found very little about such stuff on the web.
I am able to pass single string, but when I try to pass SAFEARRAY* everything stops to work.
Please help.
To simplify my code I have a function which just pass array, but doesn’t do something with it.
If I commented out Safearray from function call it works and return that “105”. The problem with SAFEARRAY. Is it possible that dll expects some other format of array?

//dll
public interface IEffDpthClc
    {
int SetCtArray(int NN, string[] CtFileArray);
    }
 
   public class EffDpthClcClass : IEffDpthClc
    {    
    …..
       public int SetCtArray(int NN , string[] CtFileArray)
        {
 
            return 105;
        }
 
…
    }
//////////////////////////////
//C++MFC  application
HRESULT hr = CoInitialize(NULL);
IEffDpthClcPtr pIEffDpthClc(__uuidof(EffDpthClcClass));
SAFEARRAY *pSA;
SAFEARRAYBOUND aDim[1];    
aDim[0].lLbound= 0;  
aDim[0].cElements=10;
pSA= SafeArrayCreate(VT_VARIANT,1,aDim); 
if (pSA != NULL)
 
{
ConvertCArrayToSmartArr(pSA );
       int z =pIEffDpthClc->SetCtArray(NN, pSA,p);
       SafeArrayDestroy(pSA);
}
CoUninitialize();
 
……
HRESULT CPlan::ConvertCArrayToSmartArr(SAFEARRAY *pSA)
{
 
        USES_CONVERSION; 
        char buffer[10];  
              HRESULT hr= S_OK;
 
            long aLong[1];
 
for (long i= 0; i< NN; i++)
 {
             VARIANT vOut;
            VariantInit(&vOut);
            vOut.vt= VT_BSTR
            ltoa(i,buffer,10);  // convert long to ANSI string value
            vOut.bstrVal= ::SysAllocString(A2W(buffer));                            aLong[0]= i;  // set index value
            if (hr= SafeArrayPutElement(pSA, aLong, &vOut))
                 {    // "correctly" copies VARIANT
                        VariantClear(&vOut);  // release BSTR from memory on error
                        SafeArrayDestroy(pSA); // does a deep destroy on error
                        return hr;
                }
                VariantClear(&vOut);  // does a deep destroy of source VARIANT
               } 
 
}

Thanks a lot.

[Elena Kr]

Sorry.
My array was not good.
It should be

HRESULT hr= S_OK;

long aLong[1];

for (long i= 0; i< NN; i++)
{
CString cs(pArray->GetAt(i));
BSTR bstr = cs.AllocSysStri ng();
aLong[0]= i; // set index value
if (hr= SafeArrayPutEle ment(pSA, aLong,bstr))
{
::SysFreeString (bstr);
SafeArrayDestro y(pSA); // does a deep destroy on error
return hr;
}
::SysFreeString (bstr);

} // end iteration

Then it works.