CB_GETCOUNT
wParam = 0; /* not used, must be zero */
lParam = 0; /* not used, must be zero */
An application sends a CB_GETCOUNT message to retrieve the number of items in the list box of a combo box.
This message has no parameters.
The return value is the number of items in the list box, or CB_ERR if an error occurs.
The returned count is one greater then the index value of the last item (the index is zero-based).