public delegate void KernelFun(); //声明委托
       static void Main(string[] args)
       {
           KernelFun kf = fun;//委托,注意不要被释放
           GC.KeepAlive(kf);//不释放kf
           IntPtr funPoint = Marshal.GetFunctionPointerForDelegate(kf);//转换为函数指针
 
           CallBack(funPoint.ToInt64(), funPoint, kf, funPoint.ToInt64().StructToBytes()); //委托传给C++调用
           Console.ReadLine();
       }
       static void fun()
       {
           Console.WriteLine("被调用了");
       }
       static int fun(int i)
       {
           Console.WriteLine("被调用了{0}",i);
           return i + i;
       }
 
       [DllImport("WINAPI.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
       public static extern bool CallBack(Int64 funpoint, IntPtr intptr, KernelFun kf ,byte[] funpointBuffer);//声明接口

typedef void(__stdcall*Pfun)(); //C++函数指针
 
DLLAPI BOOL CallBack(__int64 funpoint,INT_PTR intptr, Pfun pfun,BYTE *funpointBuffer)
{
    Pfun fun1;
    fun1 = (Pfun)(funpoint);
    fun1();
    fun1 = (Pfun)intptr;
    fun1();
    (pfun)();
    __int64  int64 = *(long long*)(funpointBuffer);
    fun1 = (Pfun)int64;
    fun1();
    fun1 = (Pfun)*(long long*)(funpointBuffer);
    fun1();
    return true;
}