QuickSort a ListView preserving ListSubItems data

[DepricatedZero]

So I'm trying to write a QuickSort for a ListView control. Built in ListView sorting is only alphabetical, not numeric, thus the need for this.

But I'm getting errors left and right. Mainly the problem is in moving the values around. It seems to be handling the rest of the quicksort logic without issue.

Typically I would just

storeItem = leftItem
leftItem = rightItem
rightItem = storeItem

however, the reassignment of the values of the listsubitems is being a reeeaaal pita. Any advice, or anyone know the 'correct' methods I should be calling on these? I've been at this for hours and can't find aaanything.

Public Sub SortByDate(ByRef lvwBox As Object, dateColumn As Integer, left As Integer, right As Integer)
    
    Dim rightIndex As Integer
    Dim leftIndex As Integer
    Dim comparisonItem As Variant
    Dim storedItem As ListItem
    
    leftIndex = left
    rightIndex = right
    comparisonItem = lvwBox.ListItems(CInt((leftIndex + rightIndex) / 2)).SubItems(dateColumn)
    
    Do
        Do While (lvwBox.ListItems(leftIndex).SubItems(dateColumn) < comparisonItem And leftIndex < rightIndex)
        leftIndex = leftIndex + 1
        Loop
        
        Do While (comparisonItem < lvwBox.ListItems(rightIndex).SubItems(dateColumn) And rightIndex > leftIndex)
        rightIndex = rightIndex - 1
        Loop


        If leftIndex <= rightIndex Then
            'This is the part giving errors. 
            Dim i As Integer
            Set storedItem = lvwBox.ListItems(leftIndex)
            
            For i = 1 To lvwBox.ListItems(leftIndex).ListSubItems.Count
                storedItem.ListSubItems.Add i, , lvwBox.ListItems(leftIndex).SubItems(i)
            Next
            
            lvwBox.ListItems.Remove leftIndex
            lvwBox.ListItems.Add (leftIndex)
            lvwBox.ListItems(leftIndex) = lvwBox.ListItems(rightIndex)
            
            For i = 1 To lvwBox.ListItems(rightIndex).ListSubItems.Count
                lvwBox.ListItems(leftIndex).ListSubItems.Add i, , lvwBox.ListItems(rightIndex).SubItems(i)
            Next
            
            lvwBox.ListItems(rightIndex) = storedItem
            
            For i = 1 To lvwBox.ListItems(leftIndex).ListSubItems.Count
                lvwBox.ListItems(rightIndex).ListSubItems.Add i, , storedItem.ListSubItems.Item(i).text
            Next
            
            leftIndex = leftIndex + 1
            rightIndex = rightIndex - 1
        End If
    Loop While leftIndex <= rightIndex
    
    If left < rightIndex Then
        SortByDate lvwBox, dateColumn, left, rightIndex
    End If
    
    If leftIndex < right Then
        SortByDate lvwBox, dateColumn, leftIndex, right
    End If
    
End Sub

[DepricatedZero]

GOT IT!

Public Sub SortByDate(ByRef lvwBox As Object, dateColumn As Integer, left As Integer, right As Integer)
    
    Dim rightIndex As Integer
    Dim leftIndex As Integer
    Dim comparisonItem As Variant
    Dim storedItem As ListItem
    
    leftIndex = left
    rightIndex = right
    comparisonItem = lvwBox.ListItems(CInt((leftIndex + rightIndex) / 2)).SubItems(dateColumn)
    
    Do
        Do While (CDate(lvwBox.ListItems(leftIndex).SubItems(dateColumn)) < CDate(comparisonItem) And leftIndex < rightIndex)
        leftIndex = leftIndex + 1
        Loop
        
        Do While (CDate(comparisonItem) < CDate(lvwBox.ListItems(rightIndex).SubItems(dateColumn)) And rightIndex > leftIndex)
        rightIndex = rightIndex - 1
        Loop
        If leftIndex <= rightIndex Then
        Debug.Print "moving"
            Dim i As Integer
            Dim movedItem As ListItem
            Set storedItem = lvwBox.ListItems(leftIndex)
            
            lvwBox.ListItems.Remove leftIndex
            Set movedItem = lvwBox.ListItems.Add(leftIndex)
            
            movedItem.text = lvwBox.ListItems(rightIndex)
            For i = 1 To lvwBox.ListItems(rightIndex).ListSubItems.Count
                movedItem.SubItems(i) = SafeInsert(lvwBox.ListItems(rightIndex).ListSubItems(i))
            Next
            
            lvwBox.ListItems(rightIndex) = SafeInsert(storedItem)
            For i = 1 To storedItem.ListSubItems.Count
                lvwBox.ListItems(rightIndex).SubItems(i) = storedItem.ListSubItems(i)
            Next
            
            leftIndex = leftIndex + 1
            rightIndex = rightIndex - 1
        End If
    Loop While leftIndex <= rightIndex
    
    If left < rightIndex Then
        SortByDate lvwBox, dateColumn, left, rightIndex
    End If
    
    If leftIndex < right Then
        SortByDate lvwBox, dateColumn, leftIndex, right
    End If
    
End Sub

Thought I'd share


oh also, for not choking on null values when you expect they might be passed

Public Function SafeInsert(lstItem As Variant) As Variant
    If IsNull(lstItem) Then
        SafeInsert = ""
    Else
        SafeInsert = lstItem
    End If
End Function

[June7]

Or deal with possible null up front, no function needed.

lvwBox.ListItems(rightIndex) = storedItem & ""

[DepricatedZero]

Putting it in a separate function is just a clean code practice I picked up from the book...Clean Code...hehe both work well. More I just wanted to give context to the function SafeInsert() that was being used all over the place.