Levenshtein distance

The Levenshtein distance between two strings is a measurement of similarity. The smaller the distance, the more similar two strings are. Our PHP programmer friends have a function to calculate this distance; we deserve one too.

ASP

1. function levenshtein(byVal first, byVal second)
2.     dim distance
3.     dim truncateLength
5.     if first = second then
6.         ' The distance is zero if the strings are identical.
7.         distance = 0


8.     else
9.         ' The distance is at least the difference of the lengths of the two strings.
10.         distance = abs(len(first) - len(second))
12.         ' Force the strings to be the same length to prevent overflows.
13.         truncateLength = ((len(first) + len(second)) - distance) / 2
14.         first = Left(first, truncateLength)
15.         second = Left(second, truncateLength)
17.         ' Compare the corresponding characters in each string.
18.         for i = 1 to truncateLength
19.             if Mid(first, i, 1) <> Mid(second, i, 1) then
20.                 distance = distance + 1
21.             end if
22.         next
23.     end if
25.     levenshtein = distance
26. end function

View ASP implementation on Snipplr