the class library name is simple
the header file is simple .h

#pragma once
using namespace System;
namespace simple
public class class1
int addition(int x, int y);


the simple.cpp is

#include "stdafx.h"

#include "simple.h"
int addition(int x, int y)
return x+y;

then i created Visual C# console app
name dlltest

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

namespace dlltest
class Program

static void Main(string[] args)
simple.class1 myobject = new simple.class1.addition();
Console.Write("the sum is:{0} ",myobject.addition(2,3));
simple.dll added in references while debugging i'm getting errors

C:\Users\admin\Documents\Visual Studio 2008\Projects\dlltest\dlltest\Program.cs(19,56): error CS0426: The type name 'addition' does not exist in the type 'simple.class1'

C:\Users\admin\Documents\Visual Studio 2008\Projects\dlltest\dlltest\Program.cs(20,60): error CS1061: 'simple.class1' does not contain a definition for 'addition' and no extension method 'addition' accepting a first argument of type 'simple.class1' could be found (are you missing a using directive or an assembly reference?)

please help me to resolve this error.