VB6 Dual-Pivot-QuickSort

[Jonney]

I change the use of tmp so If we want we can change it to string without need for another var.

Public Sub NaiveQuickSortExtended(Arr() As Long, ByVal LB As Long, ByVal UB As Long)
Dim M1 As Long, M2 As Long
Dim Piv As Long, Tmp As Long '<- adjust types here, when switching to something different than Long

     If UB - LB = 1 Then
     M1 = LB: GoTo there4
     Else
       M1 = (LB + UB) \ 2
     If Arr(M1) = Arr(LB) Then
       
     M2 = UB
     M1 = LB
    Do
         M1 = M1 + 1
         If M1 > M2 Then GoTo there3
     Loop Until Arr(M1) <> Arr(LB)
     End If
     End If
   Piv = Arr(M1)
      M1 = LB
    M2 = UB
        'create the Pivot-Element
 
    Do
      Do While (Arr(M1) < Piv): M1 = M1 + 1: Loop
      Do While (Arr(M2) > Piv): M2 = M2 - 1: Loop

      If M1 <= M2 Then
        Tmp = Arr(M1): Arr(M1) = Arr(M2): Arr(M2) = Tmp 'swap

        M1 = M1 + 1
        M2 = M2 - 1
      End If
    Loop Until M1 > M2
 
    If LB < M2 Then NaiveQuickSortExtended Arr, LB, M2
    If M1 < UB Then NaiveQuickSortExtended Arr, M1, UB
    Exit Sub
there3:
    For M1 = LB + 1 To UB - 1
        If Arr(M1) <> Arr(LB) Then Exit For
        Next M1
        
    If M1 < UB - 1 Then
        NaiveQuickSortExtended Arr(), M1, UB
    ElseIf M1 < UB Then
there4:
    If Arr(M1) > Arr(UB) Then Tmp = Arr(M1): Arr(M1) = Arr(UB): Arr(UB) = Tmp
    Else
    If Arr(UB) < Arr(LB) Then Tmp = Arr(LB): Arr(LB) = Arr(UB): Arr(UB) = Tmp
    End If
End Sub

where is the sort direction? Please make sorting routine be ready to use for beginner.