i have tried returning a collection of objects from c# and access them usig c++ via COM but failed.I have tried for List ArrayList and IDictionary all and failed.
i have tried
How to return a collection of strings from C# to C++ via COM interop also but not succeed.
can any body Help me
@Partial, you raise an important point. You cannot pass a .NET "object" back to C++ (unless it's Managed C++) because .NET object semantics are not the same as C++ object semantics.
@Cute: you can, however, pass COM Interface Pointers. If you need your "traditional C++" code to talk to .NET objects, use COM Interfaces, not objects.
Make sure your object is marked as a COM object, and that you implement a suitable Interface that contains the methods that your C++ needs. Then, pass an array of the Interface references back to the C++ code. The C++ code should get a SafeArray of COM interface pointer, which it can manipulate with the usual COM semantics (AddRef(), etc.).
How about using an old-fashioned array?
public interface IManaged
{
string[] ReturnArray();
}
public class Managed : IManaged
{
public string[] ReturnArray()
{
return new string[] { "A", "B", "C" };
}
}
Running tlbexp.exe with this .dll creates a .tlb with:
interface IManaged : IDispatch {
[id(0x60020000)]
HRESULT ReturnArray([out, retval] SAFEARRAY(BSTR)* pRetVal);
};
I have not tested using the .dll from native .exe, but it looks promising :)
It is normal that you cannot pass an object from c# to c++ or from c++ to c#. An object in c# is not like an object in c++. What you can pass from c# to c++ are types like bool, int, and char. Also, watch out for the size of types... for example a char in c# is a wchar_t in c++.
