C++中的纯虚函数在C#中如何使用使用，或者C#如何托管？？ 求大神！！！

这些是结构体
struct IIPNCMsgCallback
{
virtual int IPNCMsgNotify(WPARAM wParam, LPARAM lParam) = 0;//wParam:emCallbackMsgType lParam:IPNC_CB_DATA
};

typedef struct tagIPNC_CB_INFO
{
emCallbackNotifyType MsgNotifyType;//emCallBack:use pMsgCallback, emMSG:use nMsgID and hMsgWnd;
IIPNCMsgCallback *pMsgCallback;
unsigned int nMsgID;
HWND hMsgWnd;

#ifdef __cplusplus
tagIPNC_CB_INFO()//C++版ã?构1造¨¬函¡¥数ºy
{
ZeroMemory(this, sizeof(tagIPNC_CB_INFO));
}
#endif

}IPNC_CB_INFO, *LPIPNC_CB_INFO;

这个是设置回调
IPNC_CB_INFO cbInfo;
memset(&cbInfo,0,sizeof(IPNC_CB_INFO));
cbInfo.MsgNotifyType = emCallbackNotifyType_CallBack;
cbInfo.pMsgCallback = this;
re = CIPNCSDK::Client_SetClientCallback(&cbInfo);
if(re != emReturnOK)
{
AfxMessageBox("回?调Ì¡Â设¦¨¨置?失º¡ì败㨹");
return TRUE;
}