Levenshtein distance

<%
    ' Copyright (c) 2008, reusablecode.blogspot.com; some rights reserved.
    '
    ' This work is licensed under the Creative Commons Attribution License. To view
    ' a copy of this license, visit http://creativecommons.org/licenses/by/3.0/ or
    ' send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California
    ' 94305, USA.
 
    ' Compute the Levenshtein distance between two strings.
    function levenshtein(byVal first, byVal second)
        dim distance
        dim truncateLength
 
        if first = second then
            ' The distance is zero if the strings are identical.
            distance = 0
        else
            ' The distance is at least the difference of the lengths of the two strings.
            distance = abs(len(first) - len(second))
 
            ' Force the strings to be the same length to prevent overflows.
            truncateLength = ((len(first) + len(second)) - distance) / 2
            first = Left(first, truncateLength)
            second = Left(second, truncateLength)
 
            ' Compare the corresponding characters in each string.
            for i = 1 to truncateLength
                if Mid(first, i, 1) <> Mid(second, i, 1) then
                    distance = distance + 1
                end if
            next
        end if
 
        levenshtein = distance
    end function    
%>