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How to sort arrays of Integers, Longs, Singles, Doubles, Strings, and Variants.

Posted on June 28, 2011
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'Sorting - How to sort arrays of Integers, Longs, Singles, Doubles, Strings, and Variants.
'Use the SortIntArray, SortDoubleArray, etc. subroutines.

'Uses the quicksort algorithm.

Option Explicit
 
Private Sub QuicksortInt(list() As Integer, ByVal min As Integer, ByVal max As Integer)
    Dim med_value As Integer
    Dim hi As Integer
    Dim lo As Integer
    Dim i As Integer
 
    ' If the list has no more than CutOff elements,
    ' finish it off with SelectionSort.
    If max <= min Then Exit Sub
 
    ' Pick the dividing value.
    i = Int((max - min + 1) * Rnd + min)
    med_value = list(i)
 
    ' Swap it to the front.
    list(i) = list(min)
 
    lo = min
    hi = max
    Do
        ' Look down from hi for a value < med_value.
        Do While list(hi) >= med_value
            hi = hi - 1
            If hi <= lo Then Exit Do
        Loop
        If hi <= lo Then
            list(lo) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(lo) = list(hi)
 
        ' Look up from lo for a value >= med_value.
        lo = lo + 1
        Do While list(lo) < med_value
            lo = lo + 1
            If lo >= hi Then Exit Do
        Loop
        If lo >= hi Then
            lo = hi
            list(hi) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(hi) = list(lo)
    Loop
 
    ' Sort the two sublists.
    QuicksortInt list(), min, lo - 1
    QuicksortInt list(), lo + 1, max
End Sub
 
Private Sub QuicksortSingle(list() As Single, ByVal min As Integer, ByVal max As Integer)
    Dim med_value As Single
    Dim hi As Integer
    Dim lo As Integer
    Dim i As Integer
 
    ' If the list has no more than CutOff elements,
    ' finish it off with SelectionSort.
    If max <= min Then Exit Sub
 
    ' Pick the dividing value.
    i = Int((max - min + 1) * Rnd + min)
    med_value = list(i)
 
    ' Swap it to the front.
    list(i) = list(min)
 
    lo = min
    hi = max
    Do
        ' Look down from hi for a value < med_value.
        Do While list(hi) >= med_value
            hi = hi - 1
            If hi <= lo Then Exit Do
        Loop
        If hi <= lo Then
            list(lo) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(lo) = list(hi)
 
        ' Look up from lo for a value >= med_value.
        lo = lo + 1
        Do While list(lo) < med_value
            lo = lo + 1
            If lo >= hi Then Exit Do
        Loop
        If lo >= hi Then
            lo = hi
            list(hi) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(hi) = list(lo)
    Loop
 
    ' Sort the two sublists.
    QuicksortSingle list(), min, lo - 1
    QuicksortSingle list(), lo + 1, max
End Sub
 
Private Sub QuicksortDouble(list() As Double, ByVal min As Integer, ByVal max As Integer)
    Dim med_value As Double
    Dim hi As Integer
    Dim lo As Integer
    Dim i As Integer
 
    ' If the list has no more than CutOff elements,
    ' finish it off with SelectionSort.
    If max <= min Then Exit Sub
 
    ' Pick the dividing value.
    i = Int((max - min + 1) * Rnd + min)
    med_value = list(i)
 
    ' Swap it to the front.
    list(i) = list(min)
 
    lo = min
    hi = max
    Do
        ' Look down from hi for a value < med_value.
        Do While list(hi) >= med_value
            hi = hi - 1
            If hi <= lo Then Exit Do
        Loop
        If hi <= lo Then
            list(lo) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(lo) = list(hi)
 
        ' Look up from lo for a value >= med_value.
        lo = lo + 1
        Do While list(lo) < med_value
            lo = lo + 1
            If lo >= hi Then Exit Do
        Loop
        If lo >= hi Then
            lo = hi
            list(hi) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(hi) = list(lo)
    Loop
 
    ' Sort the two sublists.
    QuicksortDouble list(), min, lo - 1
    QuicksortDouble list(), lo + 1, max
End Sub
 
Private Sub QuicksortString(list() As String, ByVal min As Integer, ByVal max As Integer)
    Dim med_value As String
    Dim hi As Integer
    Dim lo As Integer
    Dim i As Integer
 
    ' If the list has no more than CutOff elements,
    ' finish it off with SelectionSort.
    If max <= min Then Exit Sub
 
    ' Pick the dividing value.
    i = Int((max - min + 1) * Rnd + min)
    med_value = list(i)
 
    ' Swap it to the front.
    list(i) = list(min)
 
    lo = min
    hi = max
    Do
        ' Look down from hi for a value < med_value.
        Do While list(hi) >= med_value
            hi = hi - 1
            If hi <= lo Then Exit Do
        Loop
        If hi <= lo Then
            list(lo) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(lo) = list(hi)
 
        ' Look up from lo for a value >= med_value.
        lo = lo + 1
        Do While list(lo) < med_value
            lo = lo + 1
            If lo >= hi Then Exit Do
        Loop
        If lo >= hi Then
            lo = hi
            list(hi) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(hi) = list(lo)
    Loop
 
    ' Sort the two sublists.
    QuicksortString list(), min, lo - 1
    QuicksortString list(), lo + 1, max
End Sub
 
Private Sub QuicksortVariant(list() As Variant, ByVal min As Integer, ByVal max As Integer)
    Dim med_value As Variant
    Dim hi As Integer
    Dim lo As Integer
    Dim i As Integer
 
    ' If the list has no more than CutOff elements,
    ' finish it off with SelectionSort.
    If max <= min Then Exit Sub
 
    ' Pick the dividing value.
    i = Int((max - min + 1) * Rnd + min)
    med_value = list(i)
 
    ' Swap it to the front.
    list(i) = list(min)
 
    lo = min
    hi = max
    Do
        ' Look down from hi for a value < med_value.
        Do While list(hi) >= med_value
            hi = hi - 1
            If hi <= lo Then Exit Do
        Loop
        If hi <= lo Then
            list(lo) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(lo) = list(hi)
 
        ' Look up from lo for a value >= med_value.
        lo = lo + 1
        Do While list(lo) < med_value
            lo = lo + 1
            If lo >= hi Then Exit Do
        Loop
        If lo >= hi Then
            lo = hi
            list(hi) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(hi) = list(lo)
    Loop
 
    ' Sort the two sublists.
    QuicksortVariant list(), min, lo - 1
    QuicksortVariant list(), lo + 1, max
End Sub
 
Private Sub QuicksortLong(list() As Long, ByVal min As Integer, ByVal max As Integer)
    Dim med_value As Long
    Dim hi As Integer
    Dim lo As Integer
    Dim i As Integer
 
    ' If the list has no more than CutOff elements,
    ' finish it off with SelectionSort.
    If max <= min Then Exit Sub
 
    ' Pick the dividing value.
    i = Int((max - min + 1) * Rnd + min)
    med_value = list(i)
 
    ' Swap it to the front.
    list(i) = list(min)
 
    lo = min
    hi = max
    Do
        ' Look down from hi for a value < med_value.
        Do While list(hi) >= med_value
            hi = hi - 1
            If hi <= lo Then Exit Do
        Loop
        If hi <= lo Then
            list(lo) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(lo) = list(hi)
 
        ' Look up from lo for a value >= med_value.
        lo = lo + 1
        Do While list(lo) < med_value
            lo = lo + 1
            If lo >= hi Then Exit Do
        Loop
        If lo >= hi Then
            lo = hi
            list(hi) = med_value
            Exit Do
        End If
 
        ' Swap the lo and hi values.
        list(hi) = list(lo)
    Loop
 
    ' Sort the two sublists.
    QuicksortLong list(), min, lo - 1
    QuicksortLong list(), lo + 1, max
End Sub
 
' Sort an array of integers.
Public Sub SortIntArray(list() As Integer)
    QuicksortInt list, LBound(list), UBound(list)
End Sub
 
' Sort an array of longs.
Public Sub SortLongArray(list() As Long)
    QuicksortLong list, LBound(list), UBound(list)
End Sub
 
' Sort an array of singles.
Public Sub SortSingleArray(list() As Single)
    QuicksortSingle list, LBound(list), UBound(list)
End Sub
 
' Sort an array of doubles.
Public Sub SortDoubleArray(list() As Double)
    QuicksortDouble list, LBound(list), UBound(list)
End Sub
 
' Sort an array of strings.
Public Sub SortStringArray(list() As String)
    QuicksortString list, LBound(list), UBound(list)
End Sub
 
' Sort an array of variants.
Public Sub SortVariantArray(list() As Variant)
    QuicksortVariant list, LBound(list), UBound(list)
End Sub

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