C#类库调用C++程序异常:ByRef value type parameter cannot be null,请问什么原因

[一叶之舟]

我写和C#DLL,用COM接口实现,由C++程序调用,同时C++提供接口,让C#调用,在中文操作系统下开发一直运行正常,便把程序放到英文操作系统下运行测试(我只安装了.net3.5),程序功能运行正常,就是在C#中调用C++时提示异常:ByRef value type parameter cannot be null.

下面是C#的实现:

namespace WPFCom
{
   /// <summary>
   ///  Function interface
   /// </summary>
   // To make the interface visible in COM client
   [ComVisible(true),
    // To set guid
   GuidAttribute("8DD32EFF-A446-4cb6-B6F9-0E48AD3E1A69"),
    // To set the interface type
   InterfaceType(ComInterfaceType.InterfaceIsDual)] 
   public interface IShowWin
   {
      [DispId(1)]
      void ShowWin();
   }

   /// <summary>
   /// Event interface
   /// </summary>
   [Guid("CB249F50-7649-4a91-BB99-BF189187E58A"),
   InterfaceType(ComInterfaceType.InterfaceIsIDispatch),
   ComVisible(true)]
   public interface IButtonEvent
   {
      [DispId(1)]
      void ButtonClick();
      [DispId(2)]
      void WindowClosed();
      [DispId(3)]
      double WindVoid(double p, double p1);
   }

   /// <summary>
   /// delegate for event
   /// </summary>
   /// <param name="p">
   /// message string.
   /// </param>
   public delegate void ComEvent();
   public delegate double ComEventvoid(double p, double p1);

   // Com class
   [ComVisible(true),
   GuidAttribute("36CC3A95-7430-4a3c-8D89-45C6671A2BFB"),
      // To set ICOMROTVictimEvents interface as event source.
   ComSourceInterfaces(typeof(IButtonEvent)),
      // No public memeber should be exposed.
   ClassInterface(ClassInterfaceType.None)]
   public class WPFWin : IShowWin
   {

      /// <summary>
      /// A button clicked in WPF windows
      /// </summary>
      public event ComEvent ButtonClick;
      public event ComEvent WindowClosed;
      public event ComEventvoid WindVoid;
      /// <summary>
      /// A default constructor
      /// </summary>
      public WPFWin()
      {
         m_win = new CompileXamlWindow();
         m_win.ButtonClick += OnButtonClick;
         m_win.Closed += OnWindowClosed;
      }
       /**/
      unsafe private void OnWindowClosed(object sender, EventArgs e)
      {
         if (WindowClosed != null)
         {
             try
             {
                 WindowClosed();//调用C++,此处不报异常,但不能进入C++代码
             }
             catch (System.Exception ms)
             {
                 MessageBox.Show(ms.Message);
             }
         }
      }

      /// <summary>
      /// TO show the window.
      /// </summary>
      public void ShowWin()
      {
         m_win.Show();
      }

      unsafe private void OnButtonClick()
      {
         if (WindVoid != null)
         {
             try
             {
                 ButtonClick();//调用C++,此处不报异常,但不能进入C++代码
                 double param = 1;
                 double param1 = 2;
                 WindVoid(param, param1);//调用C++,此处报异常:ByRef value type parameter cannot be null
             }
             catch (System.Exception ms)
             {
                 MessageBox.Show(ms.Message);
             }
         }
      }

      private CompileXamlWindow m_win;
   }
}

[wrinky]

能不能给一个WindVoid（）函数在c++端的代码，感觉是这里出问题了

[一叶之舟]

C+部分实现代码

class CCOMROTVictimWrapper : 
	public IDispEventImpl<0, CCOMROTVictimWrapper, &__uuidof(IButtonEvent), &__uuidof(WPFComLib), 1, 0>
{
public:
	CCOMROTVictimWrapper(void);
	virtual ~CCOMROTVictimWrapper(void);

	BEGIN_SINK_MAP(CCOMROTVictimWrapper)
        SINK_ENTRY_EX(0, __uuidof(IButtonEvent), 1, OnWPFButtonClick)
				SINK_ENTRY_EX(0, __uuidof(IButtonEvent), 2, OnWindowClosed)
				SINK_ENTRY_EX(0, __uuidof(IButtonEvent), 3, WindVoid)
	END_SINK_MAP()

	// incoming calls from the C# app
	STDMETHOD_(void, OnWPFButtonClick)(BSTR param);
	STDMETHOD_(void, OnWindowClosed)(BSTR param);
	STDMETHOD_(double, WindVoid)(double param,double param);
}

void CCOMROTVictimWrapper::OnWPFButtonClick(BSTR str)
{
	AfxMessageBox("CSharpCallsMfc param: " + CString(str));
}
void CCOMROTVictimWrapper::OnWindowClosed(BSTR str)
{
	AfxMessageBox("CSharpCallsMfc param: " + CString(str));
}

double CCOMROTVictimWrapper::WindVoid(double param,double param)
{
	AfxMessageBox("CSharpCallsMfc param: ");

}