C / C++ / MFC

BEGIN_DISPATCH_MAP(CIND890MTActiveScaleLibCtrl, COleControl)
     DISP_FUNCTION_ID(CIND890MTActiveScaleLibCtrl, "Multiplikator", DISPID_MULTI, Multiplikator, VT_R8, VTS_PR8 VTS_PR8)
END_DISPATCH_MAP()
.......
double CIND890MTActiveScaleLibCtrl::Multiplikator(double zahlE, double zahlZ)
{
	return zahlE + zahlZ;
}

class CIND890MTActiveScaleLibCtrl : public COleControl
{

	static const int DISPID_MULTI = 1025555;
............
public:
	double Multiplikator(double zahlE, double zahlZ);
}

library IND890MTActiveScaleLibLib
{
static const int DISPID_MULTI = 1025555;

[ uuid(862E674E-512D-4DCC-AE6F-AEED5F078E59),
	  helpstring("Dispatchschnittstelle für IND890MTActiveScaleLib Control")] 	dispinterface _DIND890MTActiveScaleLib
	{
		properties:
		methods:
                   [id(DISPID_MULTI)] double Multiplikator(double zahlE, double zahlZ);
        }
.......
	[ uuid(8BEE0D1C-C726-4BD8-BEE0-4BD5E0027C9B),
	  helpstring("IND890MTActiveScaleLib Control"), control ]
	coclass IND890MTActiveScaleLib
	{
		[default] dispinterface _DIND890MTActiveScaleLib;
		[default, source] dispinterface _DIND890MTActiveScaleLibEvents;
	};
}

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        AxIND890MTActiveScaleLibLib.AxIND890MTActiveScaleLib test;

        public Form1()
        {
            InitializeComponent();
        }

        private void Speichern_Click(object sender, EventArgs e)
        {
            double erg = 0, zahl1 = 1234, zahl2 = 4321;
            test.IsAccessible = true;
            erg = test.Multiplikator(zahl1, zahl2);  //!!!Type mismatch. (Exception from HRESULT: 0x80020005 (DISP_E_TYPEMISMATCH));!!!
        }
    }
}

namespace WindowsFormsApplication1
{
    partial class Form1
    {
...............
        private void InitializeComponent()
        {
.......
            this.test = new AxIND890MTActiveScaleLibLib.AxIND890MTActiveScaleLib();
            ((System.ComponentModel.ISupportInitialize)(this.test)).BeginInit();
..........            
            // 
            // test
            // 
            this.test.Enabled = true;
            this.test.CreateControl();
            this.test.Name = "test";
            this.test.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("test.OcxState")));
            this.test.TabIndex = 0;
...........
        }
    }
}