The LVM_GETISEARCHSTRING message retrieves the incremental search string of a list-view control. You can send this message explicitly or by using the ListView_GetISearchString macro.
LVM_GETISEARCHSTRING wParam = 0; lParam = (LPARAM) (LPSTR) lpsz;
Returns the number of characters in the incremental search string, or zero if the list-view control is not in incremental search mode.
The incremental search string is the character sequence that the user types while the list view has the input focus. Each time the user types a character, the system appends the character to the search string and then searches for a matching item. If the system finds a match, it selects the item and, if necessary, scrolls it into view.
A timeout period is associated with each character that the user types. If the timeout period elapses before the user types another character, the incremental search string is reset.