DWORD GetItemData( int nIndex ) const;
nIndex
Specifies the zero-based index of the item in the list box.
Retrieves the application-supplied 32-bit value associated with the specified list-box item.
The 32-bit value was the lpItem parameter of a SetItemData call.
The 32-bit value associated with the item, or LB_ERR if an error occurs.
CListBox::AddString, CListBox::InsertString, CListBox::SetItemData, LB_GETITEMDATA