VBA can't find C# dll entry point

Question

I\'m creating a dll in C# which runs a simulation when a single function runSimulation() is called. This dll should be called from VBA, as certain parameter values are given as

Answer 1

I managed to call the 'runSimulation' function in VBA code, by exposing the Simulation class through an interface in C#:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace NSSimulation
{
    public interface ISimulation
    {
        int runSimulation();
    }

    [ComVisible(true)]
    [ClassInterface(ClassInterfaceType.None)]
    public class Simulation : ISimulation
    {
        [ComVisible(true)]
        public int runSimulation()
        {
            return 0;
        }
    }
}

Then re-compile your project and export your rebuilt library with 'tlbexp.exe' from the Visual Studio command prompt:

tlbexp.exe SimulationLib.dll /out:"SimulationLib.tlb" /win64

Then open the Visual Basic editor in Excel and add a reference to 'SimulationLib.tlb' through "Tools->References->Browse". To verify

Public x As New SimulationLib.Simulation

Sub test()
   MsgBox x.runSimulation
End Sub