VBA array sort function?

I'm looking for a decent sort implementation for arrays in VBA. A Quicksort would be preferred. Or any other sort algorithm other than bubble or merge would suffice.

Please note that this is to work with MS Project 2003, so should avoid any of the Excel native functions and anything .net related.

Solution 1:

Take a look here:
Edit: The referenced source (allexperts.com) has since closed, but here are the relevant author comments:

There are many algorithms available on the web for sorting. The most versatile and usually the quickest is the Quicksort algorithm. Below is a function for it.

Call it simply by passing an array of values (string or numeric; it doesn't matter) with the Lower Array Boundary (usually 0) and the Upper Array Boundary (i.e. UBound(myArray).)

Example: Call QuickSort(myArray, 0, UBound(myArray))

When it's done, myArray will be sorted and you can do what you want with it.
_{(Source: archive.org)}

Public Sub QuickSort(vArray As Variant, inLow As Long, inHi As Long)
  Dim pivot   As Variant
  Dim tmpSwap As Variant
  Dim tmpLow  As Long
  Dim tmpHi   As Long

  tmpLow = inLow
  tmpHi = inHi

  pivot = vArray((inLow + inHi) \ 2)

  While (tmpLow <= tmpHi)
     While (vArray(tmpLow) < pivot And tmpLow < inHi)
        tmpLow = tmpLow + 1
     Wend

     While (pivot < vArray(tmpHi) And tmpHi > inLow)
        tmpHi = tmpHi - 1
     Wend

     If (tmpLow <= tmpHi) Then
        tmpSwap = vArray(tmpLow)
        vArray(tmpLow) = vArray(tmpHi)
        vArray(tmpHi) = tmpSwap
        tmpLow = tmpLow + 1
        tmpHi = tmpHi - 1
     End If
  Wend

  If (inLow < tmpHi) Then QuickSort vArray, inLow, tmpHi
  If (tmpLow < inHi) Then QuickSort vArray, tmpLow, inHi
End Sub

Note that this only works with single-dimensional (aka "normal"?) arrays. (There's a working multi-dimensional array QuickSort here.)

Solution 2:

I converted the 'fast quick sort' algorithm to VBA, if anyone else wants it.

I have it optimized to run on an array of Int/Longs but it should be simple to convert it to one that works on arbitrary comparable elements.

Private Sub QuickSort(ByRef a() As Long, ByVal l As Long, ByVal r As Long)
    Dim M As Long, i As Long, j As Long, v As Long
    M = 4

    If ((r - l) > M) Then
        i = (r + l) / 2
        If (a(l) > a(i)) Then swap a, l, i '// Tri-Median Methode!'
        If (a(l) > a(r)) Then swap a, l, r
        If (a(i) > a(r)) Then swap a, i, r

        j = r - 1
        swap a, i, j
        i = l
        v = a(j)
        Do
            Do: i = i + 1: Loop While (a(i) < v)
            Do: j = j - 1: Loop While (a(j) > v)
            If (j < i) Then Exit Do
            swap a, i, j
        Loop
        swap a, i, r - 1
        QuickSort a, l, j
        QuickSort a, i + 1, r
    End If
End Sub

Private Sub swap(ByRef a() As Long, ByVal i As Long, ByVal j As Long)
    Dim T As Long
    T = a(i)
    a(i) = a(j)
    a(j) = T
End Sub

Private Sub InsertionSort(ByRef a(), ByVal lo0 As Long, ByVal hi0 As Long)
    Dim i As Long, j As Long, v As Long

    For i = lo0 + 1 To hi0
        v = a(i)
        j = i
        Do While j > lo0
            If Not a(j - 1) > v Then Exit Do
            a(j) = a(j - 1)
            j = j - 1
        Loop
        a(j) = v
    Next i
End Sub

Public Sub sort(ByRef a() As Long)
    QuickSort a, LBound(a), UBound(a)
    InsertionSort a, LBound(a), UBound(a)
End Sub

Solution 3:

Dim arr As Object
Dim InputArray

'Creating a array list
Set arr = CreateObject("System.Collections.ArrayList")

'String
InputArray = Array("d", "c", "b", "a", "f", "e", "g")

'number
'InputArray = Array(6, 5, 3, 4, 2, 1)

' adding the elements in the array to array_list
For Each element In InputArray
    arr.Add element
Next

'sorting happens
arr.Sort

'Converting ArrayList to an array
'so now a sorted array of elements is stored in the array sorted_array.

sorted_array = arr.toarray

Solution 4:

Explanation in German but the code is a well-tested in-place implementation:

Private Sub QuickSort(ByRef Field() As String, ByVal LB As Long, ByVal UB As Long)
    Dim P1 As Long, P2 As Long, Ref As String, TEMP As String

    P1 = LB
    P2 = UB
    Ref = Field((P1 + P2) / 2)

    Do
        Do While (Field(P1) < Ref)
            P1 = P1 + 1
        Loop

        Do While (Field(P2) > Ref)
            P2 = P2 - 1
        Loop

        If P1 <= P2 Then
            TEMP = Field(P1)
            Field(P1) = Field(P2)
            Field(P2) = TEMP

            P1 = P1 + 1
            P2 = P2 - 1
        End If
    Loop Until (P1 > P2)

    If LB < P2 Then Call QuickSort(Field, LB, P2)
    If P1 < UB Then Call QuickSort(Field, P1, UB)
End Sub

Invoked like this:

Call QuickSort(MyArray, LBound(MyArray), UBound(MyArray))