Is it possible to import unmanaged class or struct from DLL using C# DllImport?

c#, c++, class, dll, dllimport

Solution

You don't need to write C++ managed code for access - but - you can't easily hop around between unmanaged and managed memory. Here's a few key points 1) Use [StructLayout(LayoutKind.Sequential)] to define .net classes that map on top of your c++ structs

[StructLayout(LayoutKind.Sequential)]
[Serializable]
public struct SFVec3F : IRawStreamIO
{
    public double _x;
    public double _y;
    public double _z;
}

2) Basic types like doubles, int32, etc move across the P/Invoke layer efficiently - more complex types earn you the .net variant of thunking - msft doco covers which data types move efficiently, try and use them

3) Everything that's a pointer in C++ land is an IntPtr in .net land and if you want to be safe you should treat it as a handle, i.e. you get the c++ side to do any manipulations/access to the underlying structure

4) Access to the native C++ is pretty straightforward (the Handle props are IntPtrs that were originally sourced on the native C++ side)

[DllImport("CS2V3.dll", CharSet = CharSet.Ansi)]
private static extern void AddChild(IntPtr csoPtr, IntPtr childPtr, short recomputeBounds, short adjustCoords, short blindchild);
public void AddChild(V3CSO theChild)
{
    AddChild(m_handle, theChild.Handle,0,0,0);
}

5) Strings and some other types require marshalling to obtain a .net usable form - note that this happens automatically for strings when you pass a string to unmanaged code, but you have to do it yourself when it's inbound

 [DllImport("CS2V3.dll", CharSet = CharSet.Ansi)]
private static extern IntPtr GetName(IntPtr csoPtr);
[DllImport("CS2V3.dll", CharSet = CharSet.Ansi)]
private static extern void SetName(IntPtr csoPtr, string newName);

   public string Name
    {
        get
        {
            IntPtr np = GetName(m_handle);
            return Marshal.PtrToStringAnsi(np);
        }
        set
        {
            SetName(m_handle, value);
        }
    }

Problem

As msdn http://msdn.microsoft.com/en-us/library/aa288468(v=vs.71).aspx says "Platform Invocation Services (PInvoke) allows managed code to call unmanaged functions that are implemented in a DLL." I want to import some class from DLL that i made in c++ Is it possible and how? for example, i have some structures inside DLL: ``` struct __declspec(dllexport) DLLVector3 { float x, y, z; }; struct __declspec(dllexport) DLLQuaternion { float x, y, z, w; }; class __declspec(dllexport) DLLCharacter { public: DLLVector3 position; DLLQuaternion orientation; DLLCharacter() { } ~DLLCharacter() { } void setPosition(PxVec3 pos) { position.x = pos.x; position.y = pos.y; position.z = pos.z; } void setOrientation(PxQuat or) { orientation.x = or.x; orientation.y = or.y; orientation.z = or.z; orientation.w = or.w; } }; struct __declspec(dllexport) PhysicalObject { DLLCharacter *character; PxRigidActor *mActor; PxController *mController; }; ``` Which way i can import those? Especially those structures with pointers

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