P/Invoke from C#: Call functions of returned object

Question

I have a native/unmanaged DLL and it has a "CreateObject" function which returns a pointer to the business object.. so the call would be sth. like:

[DllImport("MyDll.dll", CharSet = CharSet.Auto)]
private static extern IntPtr CreateObject();

Question: The object is exposing public-functions like "Connect()" which i want to call, but i don't know how to "map" these calls so i have a simple method-signature like:

private bool Connect();

Any ideas?

Answer 1

The way to do this is to provide another PInvoke function which calls into a C function that does the method call

[DllImport("MyDll.dll", CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.I1)]
private static extern bool Connect(IntPtr businessObject);

Then in C you define the following

extern "C" {
  bool Connect(Business* pObject) {
    return pObject->Connect();
  }
}