编译错误求助

[Himing]

编译错误如下：
c:\program files\microsoft visual studio\vc98\atl\include\atlcom.h(1827) : error C2259: 'CComObject<class CXXFun>' : cannot instantiate abstract class due to following members: c:\program files\microsoft visual studio\vc98\atl\include\atlcom.h(1823) : while compiling class-template member function 'long __stdcall ATL::CComCreator<class ATL::CComObject<class CXXFun> >::CreateInstance(void *,const struct _GUID &,void ** )'

here is my code:
//////////////////////////////// CXXFun class
class ATL_NO_VTABLE CXXFun
: public CComObjectRootEx<CComSingleThreadModel>
, public CComCoClass<CXXFun,&CLSID_XXFun>
, public IXXFun
{
public:
//##ModelId=39C76B50010E
char * FunName;
//##ModelId=39C76BA900FA
short ArgNum;

//##ModelId=39C773B901CC
STDMETHOD (get_FunName)(char** pVal);

//##ModelId=39C773E40320
STDMETHOD (get_ArgNum)(short* pVal);

//##ModelId=39C78A110050
STDMETHOD (Eval)(char* str, float* retval);

public:
DECLARE_REGISTRY_RESOURCEID(IDR_XXFUN)

DECLARE_PROTECT_FINAL_CONSTRUCT()

BEGIN_COM_MAP(CXXFun)
COM_INTERFACE_ENTRY(IXXFun)
END_COM_MAP()

};

////////////////////////////// IDL File
import "oaidl.idl";
import "ocidl.idl";

[
uuid(5799C4C3-8E75-11D4-842C-EFCE29846F1F),
version(1.0),
helpstring("XX 1.0 Type Library")
]
library XXLib
{
importlib("stdole32.tlb");
importlib("stdole2.tlb");


[
uuid(BCC2FC50-8E75-11D4-842C-C0A8927B4F1F),
helpstring("XXFun Class")
]
coclass XXFun
{
[default] interface IXXFun;
};

[
object,
uuid(BCC2FC51-8E75-11D4-842C-C0A8927B4F1F),
helpstring("IXXFun Interface"),
pointer_default(unique)
]
interface IXXFun : IUnkown
{
[propget, id(0)] HRESULT FunName([out, retval] char **pVal);
[propget, id(1)] HRESULT ArgNum([out, retval] short *pVal);
[helpstring("method Eval"), id(2)] HRESULT Eval([in] char *str, [out, retval] float *retval);
};
};

///////////////////////////////////////part of cpp file

BEGIN_OBJECT_MAP(ObjectMap)
OBJECT_ENTRY(CLSID_XXFun, CXXFun)
END_OBJECT_MAP()

[taolei]

com不支持char*类型，字符串操作要用BSTR,把char* 改成BSTR就可以了。

[taolei]

如果函数是按字节操作的话，把char* 改成BYTE*也可以。