怎样抛出异常

[fage87295970]

但发生错误，我是这样处理的throw new CException，但编译提示说CException，不能实例化抽象类。那该怎样抛出一个异常呢，谢谢了。

[菜牛]

从CException继承一个异常类。

[fage87295970]

class AFX_NOVTABLE CException : public CObject
{
// abstract class for dynamic type checking
DECLARE_DYNAMIC(CException)

public:
// Constructors
CException(); // sets m_bAutoDelete = TRUE
explicit CException(BOOL bAutoDelete); // sets m_bAutoDelete = bAutoDelete

// Operations
void Delete(); // use to delete exception in 'catch' block

virtual BOOL GetErrorMessage(LPTSTR lpszError, UINT nMaxError,
PUINT pnHelpContext = NULL);
virtual int ReportError(UINT nType = MB_OK, UINT nMessageID = 0);

// Implementation (setting m_bAutoDelete to FALSE is advanced)
public:
virtual ~CException() = 0;
BOOL m_bAutoDelete;
#ifdef _DEBUG
void PASCAL operator delete(void* pbData);
#if _MSC_VER >= 1200
void PASCAL operator delete(void* pbData, LPCSTR lpszFileName, int nLine);
#endif
protected:
BOOL m_bReadyForDelete;
#endif
};
对于CException在except.cpp里已经实现了其相应的虚函数了啊
CException::CException()
{
// most exceptions are deleted when not needed
m_bAutoDelete = TRUE;
#ifdef _DEBUG
m_bReadyForDelete = FALSE;
#endif
}

CException::CException(BOOL bAutoDelete)
{
// for exceptions which are not auto-delete (usually)
m_bAutoDelete = bAutoDelete;
#ifdef _DEBUG
m_bReadyForDelete = FALSE;
#endif
}

void CException::Delete()
{
// delete exception if it is auto-deleting
if (m_bAutoDelete > 0)
{
#ifdef _DEBUG
m_bReadyForDelete = TRUE;
#endif
delete this;
}
}

BOOL CException::GetErrorMessage(LPTSTR lpszError, UINT nMaxError,
PUINT pnHelpContext /* = NULL */ )
{
if (pnHelpContext != NULL)
*pnHelpContext = 0;

if (nMaxError != 0 && lpszError != NULL)
*lpszError = '\0';

return FALSE;
}

int CException::ReportError(UINT nType /* = MB_OK */,
UINT nError /* = 0 */)
{
TCHAR szErrorMessage[512];
int nDisposition;
UINT nHelpContext;

if (GetErrorMessage(szErrorMessage, _countof(szErrorMessage), &nHelpContext))
nDisposition = AfxMessageBox(szErrorMessage, nType, nHelpContext);
else
{
if (nError == 0)
nError = AFX_IDP_NO_ERROR_AVAILABLE;
nDisposition = AfxMessageBox(nError, nType, nHelpContext);
}
return nDisposition;
}
怎么还说CException是个抽象类呢

[fage87295970]

谁能回答一下呢