LB_GETSELITEMS
wParam = (WPARAM) cItems; /* maximum number of items */
lParam = (LPARAM) (int FAR*) lpItems; /* address of buffer */
An application sends an LB_GETSELITEMS message to fill a buffer with an array of integers that specify the item numbers of selected items in a multiple-selection list box.
cItems
Value of wParam. Specifies the maximum number of selected items whose item numbers are to be placed in the buffer.
lpItems
Value of lParam. Specifies a long pointer to a buffer large enough for the number of integers specified by the cItems parameter.
The return value is the actual number of items placed in the buffer. The return value is LB_ERR if the list box is a single-selection list box.