' Visual Basic 2008 9.0 .NET Examples - Searching in Arrays - Arrays : 
Module BinarySearch
    Sub Main()
        Dim base As Integer = 2
        Dim count As Integer = 10
        Dim upperbound As Integer = count - 1
        Dim numbers(upperbound) As Integer
        '
        Dim index As Integer
        For index = 0 To upperbound
            numbers(index) = (index + 1) * base
        Next
        '
        Dim number As Integer
        For number = base - 1 To base * count + 1
            ' binary search
            upperbound = count - 1
            Dim lowerbound As Integer = 0
            Dim found As Boolean = False
            Dim exhausted As Boolean = False
            Do Until found OrElse exhausted
                index = (lowerbound + upperbound) \ 2                         ' (1)
                found = (number = numbers(index))                             ' (2)
                exhausted = (upperbound <= lowerbound)                        ' (3)
                If Not (found OrElse exhausted) Then
                    If number > numbers(index) Then                           ' (4)
                        lowerbound = index + 1
                    Else
                        upperbound = index - 1
                    End If
                End If
            Loop
            ' output
            If found Then
                Console.Write(number & " found at index " & index)
            Else
                Console.Write(number & " not found")
            End If
            If exhausted Then
                Console.Write(", search exhausted")
            Else
                Console.Write(", search not exhausted")
            End If
            Console.WriteLine(", last searched " & lowerbound & " to " & upperbound)
        Next
        '
        Console.ReadLine()
    End Sub
End Module
' Visit www.studyvb.com for more examples.  Copyright 2003-2008 De Wolf.