LB_GETCOUNT
wParam = 0; /* not used, must be zero */
lParam = 0L; /* not used, must be zero */
An application sends an LB_GETCOUNT message to retrieve the number of items in a list box.
This message has no parameters.
The return value is the number of items in the list box, or it is LB_ERR if an error occurs.
The returned count is one greater than the index value of the last item (the index is zero-based).
This example retrieves the number of items in a list box:
DWORD cListItems;
cListItems = SendDlgItemMessage(hdlg, ID_MYLISTBOX, LB_GETCOUNT, 0, 0);