成员函数做接口

c#

[DllImport(".dll", CallingConvention = CallingConvention.Cdecl)]
public static extern IntPtr DllCreateObject();
//两数相加
[DllImport(".dll", CallingConvention = CallingConvention.Cdecl)]
public static extern int DllAdd(IntPtr dllObject, int a, int b);

[DllImport(".dll", CallingConvention = CallingConvention.Cdecl)]
public static extern void destoryStreamE(IntPtr dllObject);

IntPtr dllObject = DllCreateObject();
int c = DllAdd(dllObject, 1, 2);
destoryStreamE(dllObject);

c++
.h文件

#define DLL_API extern "C" _declspec(dllexport)
 class model
    {
    public:
         int i;   
		 model() {}
		 ~model() {}
        int Add(const int a, const int b)
        {
            return a + b;
        }    
    };

.cpp

DLL_API void* DllCreateObjectE()
{
	model* p = new model();
	return p;
}
DLL_API void destory(void* pCAdd) {
	model* p = (model*)pCAdd;
	return p->	~model();
};
DLL_API int DllAdd(void* pCAdd, int a, int b)
{
	model* p = (model*)pCAdd;
	return p->Add(a, b);
}