Array Ordered Linked List 1.0

Module Module1
    Const nullPtr As Integer = -1
    Dim head As Integer
    Dim freeListPtr As Integer

    Structure LinkedListNode
        Public data As Integer
        Public nxt As Integer
    End Structure

    Sub insertNode(ByRef node() As LinkedListNode, data As Integer)
        'adds node to ordered linked list
        Dim newNodePtr, previousPtr, currentPtr As Integer
        If freeListPtr <> nullPtr Then
            newNodePtr = freeListPtr
            freeListPtr = node(freeListPtr).nxt
            node(newNodePtr).data = data
            currentPtr = head
            While currentPtr <> nullPtr
                If node(currentPtr).data > data Then
                    Exit While
                End If
                previousPtr = currentPtr
                currentPtr = node(currentPtr).nxt
            End While
            If currentPtr = head Then
                node(newNodePtr).nxt = head
                head = newNodePtr
            Else
                node(newNodePtr).nxt = node(previousPtr).nxt
                node(previousPtr).nxt = newNodePtr
            End If
        Else
            Console.Error.WriteLine("Bound Error : Linked List bounds exceeded.")
        End If
    End Sub

    Sub removeNode(ByRef node() As LinkedListNode, data As Integer)
        'removes node from ordered linked list
        Dim previousPtr, currentPtr As Integer
        Dim deleteFound As Boolean
        If head <> nullPtr Then
            currentPtr = head
            While currentPtr <> nullPtr And Not deleteFound
                If node(currentPtr).data > data Then
                    Exit While
                ElseIf node(currentPtr).data < data Then
                    previousPtr = currentPtr
                    currentPtr = node(currentPtr).nxt
                Else
                    deleteFound = True
                End If
            End While
            If Not deleteFound Then
                Console.WriteLine("Node with data '" & data & "' not found - no deletes made.")
                Exit Sub
            End If
            freeListPtr = currentPtr
            If currentPtr = head Then
                head = node(currentPtr).nxt
            Else
                node(previousPtr).nxt = node(currentPtr).nxt
            End If
        Else
            Console.Error.WriteLine("Underflow Error : Cannot delete node when Linked List is empty.")
        End If
    End Sub

    Sub dumpLinkedList(node() As LinkedListNode)
        'displays contents of variables
        Console.WriteLine("head ptr " & head)
        Console.WriteLine("free ptr " & freeListPtr)
        Console.WriteLine(Environment.NewLine)
        Console.WriteLine("DATA  NEXT")
        For Each struct In node
            Console.WriteLine(struct.data & "     " & struct.nxt)
        Next
    End Sub

    Sub displayLinkedList(node() As LinkedListNode)
        'displays linked list with arrows
        Dim currentPtr As Integer = head
        Dim listToString As String
        If currentPtr <> nullPtr Then
            listToString = node(currentPtr).data
            While node(currentPtr).nxt <> nullPtr
                currentPtr = node(currentPtr).nxt
                listToString = listToString & " -> " & node(currentPtr).data
            End While
            Console.WriteLine(listToString)
        End If
    End Sub
    Sub Main()
        Dim myLinkedList() As LinkedListNode
        myLinkedList = newLinkedList(5)

        insertNode(myLinkedList, 6)
        insertNode(myLinkedList, 2)
        insertNode(myLinkedList, 8)
        insertNode(myLinkedList, 9)
        insertNode(myLinkedList, 12)
        insertNode(myLinkedList, 5)
        removeNode(myLinkedList, 8)
        insertNode(myLinkedList, 3)

        displayLinkedList(myLinkedList)
        Console.ReadLine()
    End Sub

    Function newLinkedList(maxIndex As Integer) As LinkedListNode()
        If maxIndex < 1 Then
            Console.Error.WriteLine("Index Error : Linked List max index cannot be less than 1.")
        End If
        head = nullPtr
        freeListPtr = 0
        Dim node(maxIndex) As LinkedListNode
        For i = 0 To maxIndex - 1
            node(i).nxt = i + 1
        Next
        node(maxIndex).nxt = nullPtr
        Return node
    End Function
End Module