virtual void GetWindowText(
CString& str
) const;
If the control supports the Caption stock property, this value is returned. If the Caption stock property is not supported, the value for the Text property is returned.
msdn上GetWindowText的解釋，但這是壹個虛函數，也就是說需要去看定義m_RichEdit的類裏GetWindowText是怎麽描述的，上面的問題應該在定義m_RichEdit的類裏，這個類重新定義了GetWindowText這個函數，而且參數不是CString。