MFC-GetSafeHwnd安全获取窗口句柄HWND

CWnd和HWND句柄的区别 

CWnd只能对本控件的属性进行操作， HWND还可以对子控件进行操作

CWnd*转化为HWND 

    CWnd* pWnd = GetDlgItem(IDC_BUTTON2);
    HWND hWnd = pWnd->GetSafeHwnd();//CWnd*转化为HWND
    ::SetWindowText(hWnd,_T("测试"));