[RESOLVED] [3.0/LINQ] DLLImport from a C++ DLL

[steve_rm]

Hello,

VS 3.5

I have created a simple C++ DLL, and I want to use this in my C# program.

However, I am getting a Can't find PInvoke DLL 'TEST_SIP.dll

I have placed the DLL in my debug folder where my C# program is executed from. I am not sure if that is the correct place to put it.

Not sure where I am going wrong with this one.

many thanks for any suggestions,

Steve

Code in my C#

[DllImport("TEST_SIP.dll")]
        public static extern double Add(double a, double b);

         private void btnLogin_Click_1(object sender, EventArgs e)
        {
            string msg = SendData("Hello how are you");//Can't find PInvoke DLL 'TEST_SIP.dll'.
            MessageBox.Show(msg);
        }

C++ header

//TEST_SIP.h
#include <iostream>

namespace TEST_SIP
{
	class TEST_SIP_Phone
	{
	public:
		static _declspec(dllexport) double Add(double a, double b);
		static _declspec(dllexport) double Subtract(double a, double b);
		static _declspec(dllexport) double Multiply(double a, double b);
		static _declspec(dllexport) double Divide(double a, double b);
		static _declspec(dllexport) std::string SendData(std::string data);
	};
}

C++ Functions

//TEST_SIP.cpp
#include "TEST_SIP.h"
#include <stdexcept>
#include <cctype>

using namespace std;

namespace TEST_SIP
{
	double TEST_SIP_Phone::Add(double a, double b)
	{
		return a + b;
	}
	double TEST_SIP_Phone::Subtract(double a, double b)
	{
		return a - b;
	}
	double TEST_SIP_Phone::Multiply(double a, double b)
	{
		return a * b;
	}
	double TEST_SIP_Phone::Divide(double a, double b)
	{
		if(b == 0)
		{
			throw new invalid_argument("b cannot be zero!");
		}

		return a / b;
	}
	std::string TEST_SIP_Phone::SendData(std::string data)
	{
		return data;		
	}	
}