C++/CLI DLL linker issue - c++

Question

Ok so I am trying to create a runtime DLL for another application that can be called using GetProcAddress.
So I have built the DLL in VS2012 C++ Express (Header and source below) and it returns NULL even when dll is in same folder as exe. So this lead me to believe there was an issue with the dllmain function. So I began looking through MSDN and found the following link
http://msdn.microsoft.com/en-us/library/vstudio/988ye33t.aspx
It states that it is already taken care for me when I create dll template which I did following this MSDN link.
http://msdn.microsoft.com/en-us/library/ms235636%28v=vs.80%29.aspx
So I decided to try build the DLL in release mode (thinking something about this might be the issue) but I get a linker error saying entry point must be define. It builds fine in debug mode but not in release mode. I assume I am missing something simple here.
Error 1 error LNK1561: entry point must be defined C:\Users\ProRip\Documents\Visual Studio 2012\Projects\PhantomAdapter\AdapterDLL\LINK AdapterDLL
Header
#ifdef PHANTOMADAPTER_EXPORTS
#define PHANTOMADAPTER_API __declspec(dllexport)
#else
#define PHANTOMADAPTER_API __declspec(dllexport)
#endif
#using <mscorlib.dll>
#using <system.dll>
using namespace System;
using namespace System::IO::Ports;
using namespace System::Threading;
namespace PhantomAdapter
{
class PhantomAdapter
{
public:
static PHANTOMADAPTER_API int open();
static PHANTOMADAPTER_API int close();
//static PHANTOMADAPTER_API double init(bool );
//static PHANTOMADAPTER_API int noDevices();
static PHANTOMADAPTER_API int angle(double& angle);
static PHANTOMADAPTER_API int torque(double torque);
static PHANTOMADAPTER_API int ready();
};
public ref class SerialPort
{
private:
static System::IO::Ports::SerialPort^ p1;
public:
static int openPort();
static void closePort();
static int read();
static void send(Byte data);
static int check();
};
}
Source
#include "stdafx.h"
#include "stdafx.h"
#include "PhantomAdapter.h"
#include <stdexcept>
using namespace std;
namespace PhantomAdapter
{
int PhantomAdapter::open()
{
int flag=0;
flag=SerialPort::openPort();
return flag;
}
int PhantomAdapter::close()
{
SerialPort::closePort();
return 1;
}
int PhantomAdapter::angle(double& angle)
{
SerialPort::send(0x82);
angle = (SerialPort::read() * 255) + (SerialPort::read());
angle = angle*(6.2832/512);
return 1;
}
int PhantomAdapter::torque(double torque)
{
return 1;
}
int PhantomAdapter::ready()
{
return SerialPort::check();
}
int SerialPort::openPort()
{
bool check=0;
p1 = gcnew System::IO::Ports::SerialPort();
p1->BaudRate = 57600;
p1->PortName = "COM3";
if(p1->IsOpen)
return 0;
else {
p1->Open();
return 1;
}
}
int SerialPort::check()
{
array<String^>^ serialPorts = nullptr;
int flag=0;
serialPorts = p1->GetPortNames();
for each(String^ port in serialPorts)
{
if(port=="COM3")
flag=1;
}
return flag;
}
void SerialPort::closePort()
{
p1->Close();
}
void SerialPort::send(Byte data)
{
array<unsigned char>^ buffer = gcnew array<Byte>(1);
buffer[0] = (char)data;
p1->Write(buffer,0,1);
}
int SerialPort::read()
{
return p1->ReadByte();
}
}

Answer 1

In your VS project, can you check the settings:
1. Configuration Properties > General > Configuration Type? Is this set to .dll in case of Release mode?
2. Configuration Properties > Linker > System > SubSystem? Is this the same between the 2 modes?

Answer 2

You cannot call a .NET method (and C++/CLI methods are .NET methods) from native code via LoadLibrary/GetProcAddress. .NET methods and classes are not exported that way. You will always get a NULL pointer.
What you can do:
Write a COM component in .NET to reference in plain C++
Export normal, plain C++ methods that call .NET code only internally
Import a managed dll into a managed (the same C++/CLI or C# or any other .NET language) executable by using the Assembly class and it's methods.