Question

I need to write a .NET Managed wrapper for C++ function defined as follows:

void getMap(CMapStringToString*& Map);

This function stores in the necessary information in the Map variable.

Now I wrapped the function as follows but I somehow do not get the correct output from the wrapped function:

void GetMap(System::Collections::Specialized::StringDictionary ^% nMap)
{
  CMapStringToString orig_map, *map = &orig_map, *&mapRef = map;
  m_pUnmanagedObject->getMap(mapRef);
  for(POSITION pos = orig_map.GetStartPosition(); pos != NULL; )
  {
    CString key, pa, &paRef = pa;
    orig_map.GetNextAssoc(pos, key, paRef);
    nMap->Add(gcnew System::String((LPCTSTR)key), gcnew System::String((LPCTSTR)pa));
  }
}

There is definitely something wrong with the wrapper because when I use the C++ code I get the correct output but when I use the wrapper code, the nMap is empty (i.e. in C# when I did nMap.Count, it returned 0 whereas for that same example in C++ I was getting 6)

Answer 1

Replace

orig_map.GetStartPosition()

and

orig_map.GetNextAssoc(...

with

(*mapRef).GetStartPosition()

and

(*mapRef).GetNextAssoc(...