An application sends a CB_GETITEMDATA message to a combo box to retrieve the application-supplied 32-bit value associated with the specified item in the combo box.
CB_GETITEMDATA
wParam = (WPARAM) index; // item index
lParam = 0; // not used; must be zero
The return value is the 32-bit value associated with the item. If an error occurs, it is CB_ERR.
If the item is in an owner-drawn combo box created without the CBS_HASSTRINGS style, the return value is the 32-bit value contained in the lParam parameter of the CB_ADDSTRING or CB_INSERTSTRING message that added the item to the combo box. If the CBS_HASSTRINGS style was not used, the return value is the lParam parameter contained in a CB_SETITEMDATA message.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Combo Boxes Overview, Combo Box Messages, CB_ADDSTRING, CB_INSERTSTRING, CB_SETITEMDATA