Sorting an array

[JaredM]

Does anyone have any optimized code for array sorting?

[plenderj]

Numerical or string ?

[Ali G]

i don't knows abou' optimizd, but dis code from me main man Aarn Young is wicked, respeck

Public Sub Sort(ByRef aArray As Variant)
    Dim lCount As Long, lCount2 As Long
    Dim vTemp As Variant
    Dim vItem1 As Variant, vItem2 As Variant
    
    For lCount = LBound(aArray) To UBound(aArray) - (1 - LBound(aArray))
        For lCount2 = LBound(aArray) To UBound(aArray) - (1 - LBound(aArray)) - lCount
            vItem1 = aArray(lCount2 + 1)
            vItem2 = aArray(lCount2)
            If vItem1 < vItem2 Then
                vTemp = aArray(lCount2)
                aArray(lCount2) = aArray(lCount2 + 1)
                aArray(lCount2 + 1) = vTemp
            End If
        Next
    Next
End Sub

[plenderj]

Pfft.
This ownz. I wrote it.

Option Explicit
 
Private Function sortInts(arrInt() As Long) As Long()
    Dim i As Long, tempN As Long, allOk As Boolean
    Do
        allOk = True
        For i = 0 To UBound(arrInt) - 1
            If arrInt(i) > arrInt(i + 1) Then
                allOk = False
                tempN = arrInt(i)
                arrInt(i) = arrInt(i + 1)
                arrInt(i + 1) = tempN
            End If
        Next
        If allOk Then Exit Do
    Loop
    sortInts = arrInt
End Function
 
Private Sub Form_Load()
    Dim x() As Long, i As Long
    ReDim x(10)
    For i = 0 To 10
        x(i) = CLng(Rnd * 1000)
        Debug.Print x(i)
    Next
    x = sortInts(x)
    
    For i = 0 To 10
        Debug.Print x(i)
    Next
End Sub

[jim mcnamara]

What these guys showed is great for smaller lists, There a bunch of other sorting algorithms, and each one is 'optimized' for a particular task.

In general a quicksort is the fastest easy-to-code algorithm.

However, MS has built-in fast sorting algorithms for use in controls. ListBox.Sorted = True makes a listbox sort any items added to it. All you have to do is to add the items, then read them back. No sorting. You have to lpad numeric value. There are limits to the size of the array when you do this - 32767 items.

For i=0 to ubound(myArr)
        List1.AddItem myArr(i)
Next
For i = 0 to List1.ListCount - 1
       myArr(i) = list1.list(i)
next

If you work with numeric values, use lpad

Function lpad(i as integer, iLen as integer) as string
           Dim tmp as string
           tmp = cstr(i)
           lpad = right(Space(iLen) & tmp,iLen)
End function
'sorting numbers 
For i=0 to ubound(myArr)
        List1.AddItem lpad(myArr(i),10)
Next
For i = 0 to List1.ListCount - 1
       myArr(i) = Cint(list1.list(i))
next

[plenderj]

My algorithm is good with huge lists too I might mention.
But anyway if you want to use the listbox approach, hide it, then add the items, then unhide it.

[jim mcnamara]

Jamie - your algorithm is a bubblesort. The number of operations goes up exponentially as a function of list length. If the list is already in reasonable shape, this algorithm is perfect. It's the best choice. However. If the order is completely random the number of operations is:

operations = (n-1) ^ 2

For a quicksort on the same random array:

operations = log(n-1) ^ 2

The number of operations (time consumed) goes up a lot slower as you add more & more items to a quicksort as compared to a bubblesort.

[plenderj]

Correction, if the list is completely random, statistically speaking its (n - 1) ^ 2 operations

[jim mcnamara]

Hey! good - you've been reading your CS texts. Keep us all in line out here.

[plenderj]

Nah not reading anything. Just common sense...
Anyway I didnt know the algorithm I gave had a name. It just came to me while I was sitting here doing nothing...