[VB.net] Modified Merge Sort

[krunchy11]

A sorting function I created - It is based on the Merge Sort algorithm.

I know sorting functions are not really needed anymore and this one still needs a bit of refinement. Still I thought I might share it since I created it.

Public Sub splitsort1(ByRef pvarArray() As VariantType, Optional ByVal leftpos As Integer = 0, Optional ByVal rightpos As Integer = -2)
        'filling initial array size - needed at start
        If rightpos = -2 Then
            rightpos = pvarArray.Length - 1
        End If
        'checking if recursion needs to end making sure both positions are not equal or right is greater than left
        If rightpos <> leftpos And rightpos > leftpos Then
            Dim rcount As Integer = 0
            Dim temp As VariantType = VariantType.Null
            Dim count As Integer = 0
            Dim l1 As Integer = leftpos
            'declaring midpoint
            Dim mid As Integer = pvarArray((rightpos - leftpos + 1) \ 2 + leftpos)
            Dim tvararray(pvarArray.Length - 1) As VariantType
            tvararray = pvarArray.Clone()
            'Looping to put elements into two groups around midpoint
            For l As Integer = leftpos To rightpos
                If pvarArray(l) < mid Then
                    'left pile
                    tvararray(leftpos) = pvarArray(l)
                    leftpos += 1
                Else
                    If pvarArray(l) = mid Then
                        'mid removed
                        temp = pvarArray(l)
                        count += 1
                    Else
                        'right pile
                        tvararray(rightpos - rcount) = pvarArray(l)
                        rcount += 1
                    End If
                End If
            Next
            'filling midpoint/s in array - these are in their final position
            For x = 1 To count
                tvararray(leftpos + x - 1) = temp
            Next
            pvarArray = tvararray.Clone()
            'recursion left
            splitsort1(pvarArray, 0 + l1, leftpos - 1)
            'recursion right
            splitsort1(pvarArray, leftpos + count, leftpos + rcount + count - 1)
        End If
    End Sub

[minitech]

You shouldn't use VariantType, it can make some really bad code and reduce efficiency. Instead, use templating (Google it!). Also, for another small efficiency improvement, use AndAlso instead of And.