q2.cpp

class CWidget
{
    ...
 
public:
    CEventListener* m_ppEventListeners;
    int m_EventListenerCount;
 
private:
    CWidget* m_pFirstChild;
    CWidget* m_pSibling;
};
 
 
void DestroyWidget(CWidget *pRoot)
{
    if(pRoot != 0)
    {
        if(pRoot->m_ppEventListeners != 0) 
        {
            for(int j = 0; j < pRoot->m_EventListenerCount; ++j)
            {
                pRoot->m_ppEventListeners[j]->UnRegister(pRoot);
            }
 
            delete pRoot->m_ppEventListeners;
        }
 
        CWidget *pChild = pRoot->GetFirstChild();
        while(pChild)
        {
            DestroyWidget(pChild);
            pChild = pChild->GetSibling();
        }
    }
 
    delete pRoot;
}