CBN_SELCHANGE in Dynamically created ComboBoxes - c++

Question

How to get the CBN_SELCHANGE in dynamically created CComboBoxes??.. I used a array of CComboBoxes.
MyCComboBox * p_ComboBoxes = new MyCComboBox[numberOcComboBoxes]; //numberOcComboBoxes determined at rumtime
In the message Map of MyCComboBox
BEGIN_MESSAGE_MAP(MyCComboBox , CComboBox)
ON_CONTROL_REFLECT(CBN_SELCHANGE, &CTestDlg::OnCbnSelchange)
END_MESSAGE_MAP()
void CTestDlg::OnCbnSelchange()
{
this->GetDlgCtrlID(); // Get The ComboBox ID;
CString sText;
p_ComboBoxes[0].GetLBText(p_ComboBoxes[0].GetCurSel() , sText); // I can't access like this
}
// Initialization of the p_ComboBoxes Array..
for (int i = 0 ;i < iNumber ; i++)
{
p_ComboBoxes[i].Create(WS_CHILD|WS_VISIBLE|WS_VSCROLL|CBS_DROPDOWN,
CRect(10 + MY_PIC_ADDITIONAL_WIDTH,iItemDrawHeight,10 + MY_PIC_ADDITIONAL_WIDTH +MY_PIC_PROPERTY_WIDTH
,iItemDrawHeight +MY_PIC_HEIGHT), this, pImageControlPropertyID[i]);
iItemDrawHeight += MY_PIC_PROPERTY_ADDITIONAL_HEIGHT;
}
I can't access the selected text it gives me "Access violation reading location 0x00000020" error..

Answer 1

As already mentioned, ON_CONTROL_REFLECT is for handling the message in the control class, not in the parent dialog class. You should be implementing your OnCbnSelchange() handler in the MyCComboBox class and adding an ON_CONTROL_REFLECT entry in the MyCComboBox message map.
If you really want to handle the message in the parent dialog, you should use the ON_CONTROL macro - one entry for each child combo each with a separate handler so you can tell which one sent the message.

Answer 2

You could also override OnCommand(WPARAM wParam, LPARAM lParam)
in the parent dialog window. If HIWORD(wParam) == CBN_SELCHANGE, then compare
LOWORD(wParam) against the id's of your controls.
BOOL CMyDlg::OnCommand(WPARAM wParam, LPARAM lParam)
{
if(HIWORD(wParam) == CBN_SELCHANGE) { //A combo box selection changed
int ID = LOWORD(wParam); //The ID of the corresponding ComboBox
//Perform additional handling...
}
return CDialog::OnCommand(wParam, lParam);
}