Copy Class Object, destroy original object, why copy becomes NULL?

[KeanHeng]

Guys...



Basically, I'm trying to clone a class object. Then delete original. But my copy also becomes NULL?


Can anyone explain why this happened? And how to do proper clone copy?



// library
m_dataPage.SetInfo(dtStartTime, dtEndTime, false);
InsertSubPage(&m_dataPage);
CreateSheet(); // display as full screen

// application level, manipulate object to display as TabControl
CPropertyPage* pg_copy = dynamic_cast<CPropertyPage*>(&m_dataPage);

m_tabCtrl.AddTab("My Tab Pages",pg_copy); // ? pg_copy = NULL when m_dataPage is deleted
DeletePage(&m_dataPage);

Please advise....

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