Question

I was wondering how to compare 2 lists, via string or array, and acquire the values that did not compare.

I’m thinking of something similar to the PHP function array_diff().

Is it possible with classic ASP?

Answer 1

You could use Scripting.Dictionary:

Public Function RemoveMatches(byVal arrRemove(), byVal arrMatches)
    Dim sdScriptingDictionary, Item, arrReturn

    Set sdScriptingDictionary = CreateObject("Scripting.Dictionary")
    sdScriptingDictionary.RemoveAll
    sdScriptingDictionary.CompareMode = BinaryCompare
    For Each itemRemove in arrRemove
        For Each itemMatches in arrMatches
            If itemMatches<>itemRemove Then
                'Response.Write "ADD:" & itemRemove & ":" & itemMatches & "<br />"
                If Not sdScriptingDictionary.Exists(itemRemove) Then sdScriptingDictionary.Add itemRemove, itemRemove
            Else
                'Response.Write "REMOVE:" & itemRemove & ":" & itemMatches & "<br />"
                If sdScriptingDictionary.Exists(itemRemove) Then sdScriptingDictionary.Remove(itemRemove)
                Exit For
            End If
        Next
    Next
    arrReturn = sdScriptingDictionary.keys

    'Clean Up
    Erase arrRemove
    Set arrRemove = Nothing

    Erase arrMatches
    Set arrMatches = Nothing

    sdScriptingDictionary.RemoveAll
    Set sdScriptingDictionary = Nothing

    RemoveMatches = arrReturn
End Function