BinarySearch – Fast search in a sorted array

' Binary search in an array of any type' Returns the index of the matching item, or -1 if the search fails'' The arrays *must* be sorted, in ascending or descending' order (the routines finds out the sort direction).' LASTEL is the index of the last item to be searched, and is' useful if the array is only partially filled.'' Works with any kind of array, including objects if your are searching ' for their default property, and excluding UDTs and fixed-length strings.' String are compared in case-sensitive mode.'' You can write faster procedures if you modify the first line' to account for a specific data type, eg.'   Function BinarySearchL (arr() As Long, search As Long,'  Optional lastEl As Variant) As LongFunction BinarySearch(arr As Variant, search As Variant, _    Optional lastEl As Variant) As Long    Dim index As Long    Dim first As Long    Dim last As Long    Dim middle As Long    Dim inverseOrder As Boolean        ' account for optional arguments    If IsMissing(lastEl) Then lastEl = UBound(arr)        first = LBound(arr)    last = lastEl    ' deduct direction of sorting    inverseOrder = (arr(first) > arr(last))    ' assume searches failed    BinarySearch = first - 1        Do        middle = (first + last)  2        If arr(middle) = search Then            BinarySearch = middle            Exit Do        ElseIf ((arr(middle) < search) Xor inverseOrder) Then            first = middle + 1        Else            last = middle - 1        End If    Loop Until first > lastEnd Function