C#

An unhandled exception of type 'System.NullReferenceException' occurred in MariaTestCSharp.exe

Additional information: Object reference not set to an instance of an object.

public class Form1 : System.Windows.Forms.Form
{
   ...

   public delegate int OnStartCallback( ref Guid GUID );
   private OnStartCallback myCallback;

   [DllImport("Maria.dll")]
   public static extern int CAPI_InitMaria( IntPtr hWndParent, IntPtr hResource, 
      OnStartCallback pInitFunction, int nFlags );

   public static int OnStart( ref Guid GUID )
   {
      return 0;
   }

   private void initMaria_Click(object sender, System.EventArgs e)
   {
      System.Reflection.Module[] modules = 
         System.Reflection.Assembly.GetExecutingAssembly().GetModules(true);

      instancePtr = Marshal.GetHINSTANCE( modules[0] );

      myCallback = new OnStartCallback( OnStart );

      CAPI_InitMaria( panel1.Handle, instancePtr, myCallback, 
         0x0004 /* Don't show splash screen */);

   }

   ...
}

typedef int (*procCAPI_OnMariaStartup)( const GUID* pInstanceID );

typedef HWND(*procCAPI_InitMaria)( HWND hWndParent, HINSTANCE hResource,
   procCAPI_OnMariaStartup pInitFunction, int nFlags );