Transferring data from unmanaged code to managed code

Question

I have a three layer application:

• C # managed layer.
• C ++ / cli managed layer.
• Unmanaged C ++ level.

The second level is used as the level of communication between C # and native C ++.

public class ManagedResult
{
  public float[] firstArray;
  public float[] secondArray;
}

and unmanaged class

 class UnmanagedResult
    {
      public:
         float* firstArray, secondArray;
         int arrayLength;
         UnmanagedResult(){};
         ~UnmanagedResult(){};
    }

At the second level, I have the following class method that displays a managed object:

 ManagedResult^ CLIContext::GetResults(){

   ManagedResult^ primitiveResult = gcnew ManagedResult();

   pin_ptr<int> pFirst = &(primitiveResult->firstArray[0]);
   pin_ptr<float> pSecond = &(primitiveResult->secondArray[0]);
   UnmanagedResult result =UnmanagedResult();
   result.firstArray = pFirst;
   result.secondArray = pSecond;

   _context->GetResults(result);

   return primitiveResult;

 }

Here _context is an object of an unmanaged class type that manipulates an object of type UnmanagedResult and affects its contents.

This solution is working fine. But I want to be able to pass an object by reference and using a third-party API to distribute and populate the two elements firstArrayand secondArray. How to transfer data from an unmanaged result back to primitiveResult?

Answer 1

- , .

, . , .

System::Runtime::InteropServices::Marshal::Copy :

UnmanagedResult unmanagedResult = GetTheUnmanagedResultSomehow();
ManagedResult^ managedResult = gcnew ManagedResult();

managedResult->firstArray = gcnew array<float>(unmanagedResult.arrayLength);
Marshal::Copy(IntPtr(unmanagedResult.firstArray), managedResult->firstArray, 0, managedResult->firstArray->Length); 

// Do the same for secondArray