DWORD GetItemData( int nIndex ) const;
nIndex
Contains the zero-based index of an item in the combo box's list box.
Retrieves the application-supplied 32-bit value associated with the specified combo-box item. The 32-bit value can be set with the dwItemData parameter of a SetItemData member function call.
The 32-bit value associated with the item, or CB_ERR if an error occurs.
CComboBox::SetItemData, CB_GETITEMDATA