class c {
private:
	int count;
public:
	void add(int n);
	int get();
};

void C:: add(int n){
	count += n;
}

int C:: get(int n){
	return count;
}

extern
 
"C" __declspec(dllexport) c* establishC()
{
    c* obj1 = new c;
    return obj1;
}

extern"C" __declspec(dllexport) void addCount(c* obj1, int n)
{
    obj1->add(n);
    return obj1;
}

extern"C" __declspec(dllexport) int getCount(c* obj1)
{
    return obj1->get();
}

public class
 
 c {
    [dllimport "filename.dll"]
    public static extern IntPtr establishC();
    [dllimport "filename.dll"]
    public static extern void addCount(IntPtr obj1, int n);
    [dllimport "filename.dll"]
    public static extern int getCount(IntPtr obj1);
}

IntPtr obj;
obj =
 
 c.establishC();
c.addCount(1);
int num = c.getCount();