Option Strict Off
Imports System
Imports System.IO
Imports System.Runtime.Serialization
Imports System.Runtime.Serialization.Formatters.Binary
Public Module SerializationSample
    ‘Class Node to hold the Linklist Item. Must be marked as
    ‘serializable
     Public Class Node
        Public Value As Integer
        Public NextNode As Node = Nothing
        ‘Constructor
        Public Sub New(ByVal NewValue As Integer)
            MyBase.New()
            Me.Value = NewValue
        End Sub
    End Class
    ‘Linked List Class.  MUst be marked with
    ‘serializable attribute
     Public Class LinkedList
        Private m_head As Node = Nothing
        Private m_tail As Node = Nothing
        ‘Adding to Linklist
        Public Function Add(ByVal iValue As Integer) As Boolean
            Dim curNode As Node = m_head
            While Not (curNode Is Nothing)
                If (curNode.Value = iValue) Then Return False
                curNode = curNode.NextNode
            End While
            Dim newNode As Node = New Node(iValue)
            If (m_tail Is Nothing) Then
                m_tail = newNode
                m_head = m_tail
            Else
                m_tail.NextNode = newNode
                m_tail = newNode
            End If
            Return True
        End Function
        ‘Remove from link list
        Public Function Remove(ByVal iValue As Integer) _
              As Boolean
            Dim prevNode As Node = Nothing
            Dim curNode As Node = m_head
            While Not (curNode Is Nothing)
                If (curNode.Value = iValue) Then
                    If (prevNode Is Nothing) Then
                        If (m_head Is m_tail) Then
                            m_tail = Nothing
                            m_head = m_tail
                        Else
                            m_head = m_head.NextNode
                        End If
                    Else
                        prevNode.NextNode = curNode.NextNode
                        Exit While
                    End If
                    Return True
                End If
                prevNode = curNode
                curNode = curNode.NextNode
            End While
            Return False
        End Function
        ‘Find a specific node in linklist
        Public Function FindNode(ByVal iValue As Integer) As Node
            Dim curNode As Node = m_head
            While Not (curNode Is Nothing)
                If curNode.Value = iValue Then Return curNode
                curNode = curNode.NextNode
            End While
            Return Nothing
        End Function
        ‘Swap the Node position in linked list
        Public Function SwapPositions(ByVal iValue1 As Integer, _
          ByVal iValue2 As Integer) As Boolean
            Dim curNode As Node = m_head
            Dim Node1 As Node = Nothing
            Dim Node2 As Node = Nothing
            Dim prevNode As Node = Nothing
            Dim prevNode1 As Node = Nothing
            Dim prevNode2 As Node = Nothing
            If iValue1 = iValue2 Then
                Return False
            End If
            While Not (curNode Is Nothing)
                If (curNode.Value = iValue1) Then
                    prevNode1 = prevNode
                    Node1 = curNode
                ElseIf (curNode.Value = iValue2) Then
                    prevNode2 = prevNode
                    Node2 = curNode
                End If
                If (Not (Node1 Is Nothing)) And (Not (Node2 Is Nothing)) Then
                    Exit While
                End If
                prevNode = curNode
                curNode = curNode.NextNode
            End While
            If Node1 Is Nothing Or Node2 Is Nothing Then _
                 Return False
            If (prevNode1 Is Nothing) Then
                m_head = Node2
            Else
                prevNode1.NextNode = Node2
            End If
            If (prevNode2 Is Nothing) Then
                m_head = Node1
            Else
                prevNode2.NextNode = Node1
            End If
            Dim tmp As Node = Node1.NextNode
            Node1.NextNode = Node2.NextNode
            Node2.NextNode = tmp
            Return True
        End Function
        ‘Display
        Public Sub Draw()
            Dim curNode As Node = m_head
            Debug.Write(“List: ”)
            While Not (curNode Is Nothing)
                Debug.Write(curNode.Value & ”  ”)
                curNode = curNode.NextNode
            End While
            Debug.WriteLine(“”)
        End Sub
    End Class
    ‘Serialization implementation.
    Public Class Ser
        ReadOnly iMinValue As Integer = 1
        ReadOnly iMaxValue As Integer = 9
        Public Sub Scope1()
            Dim list As LinkedList = New LinkedList()
            Dim i As Integer
            Debug.WriteLine(“Entering Scope 1”)
            Debug.WriteLine(“Creating and filling List ..”)
            For i = iMinValue To iMaxValue – 1
                list.Add(i)
            Next
            SaveListToDisk(list)
            Debug.WriteLine(“Leaving Scope 1\n”)
        End Sub
        Public Sub Scope2()
            Debug.WriteLine(“Entering Scope 2”)
            Dim list As LinkedList = LoadListFromDisk()
            Debug.WriteLine(“Swapping Entries”)
            Debug.WriteLine(“Swapping 1 and 2”)
            list.SwapPositions(1, 2)
            Debug.WriteLine(“Swapping 3 and 4”)
            list.SwapPositions(3, 4)
            Debug.WriteLine(“Swapping 5 and 6”)
            list.SwapPositions(5, 6)
            Debug.WriteLine(“Swapping 7 and 8”)
            list.SwapPositions(7, 8)
            SaveListToDisk(list)
            Debug.WriteLine(“Leaving Scope 2\n”)
        End Sub
        Public Sub Scope3()
            Debug.WriteLine(“Entering Scope 3”)
            Dim list As LinkedList = LoadListFromDisk()
            Debug.WriteLine(“Swapping Random Entries”)
            Dim rnd As Random = New Random()
            Dim num1, num2, i As Integer
            For i = 0 To 15
                While (True)
                    num1 = rnd.Next(iMinValue, iMaxValue + 1)
                    num2 = rnd.Next(iMinValue, iMaxValue + 1)
                    If num1 <> num2 Then
                        Exit While
                    End If
                End While
                Debug.WriteLine(“Swapping ” & num1 _
                      & ” and ” & num2)
                list.SwapPositions(num1, num2)
            Next
            SaveListToDisk(list)
            Debug.WriteLine(“Leaving Scope 3\n”)
        End Sub
        Public Sub Scope4()
            Debug.WriteLine(“Entering Scope 4”)
            Dim list As LinkedList = LoadListFromDisk()
            Debug.WriteLine(“Removing Entries”)
            Debug.WriteLine(“Removing 1”)
            list.Remove(1)
            Debug.WriteLine(“Removing 2”)
            list.Remove(2)
            Debug.WriteLine(“Removing 3”)
            list.Remove(3)
            SaveListToDisk(list)
            Debug.WriteLine(“Leaving Scope 4\n”)
        End Sub
        Private Function LoadListFromDisk() As LinkedList
            Debug.WriteLine _
                (“Deserializing LinkedList from file ..”)
            Dim s As Stream = New FileStream(“linkedlist.bin”, FileMode.Open)
            Dim b As BinaryFormatter = New BinaryFormatter()
            ‘This casting requires option strict option of vb to
            ’ be off
            ‘While compliing the code use the
            ’ switch /optionstrict-
            Dim list As LinkedList = b.Deserialize(s)
            s.Close()
            list.Draw()
            Return list
        End Function
        Private Sub SaveListToDisk(ByRef list As LinkedList)
            list.Draw()
            Debug.WriteLine _
             (“Serializing LinkedList to file ..”)
            Dim s As Stream = New FileStream(“linkedlist.bin”, FileMode.Create)
            Dim b As BinaryFormatter = New BinaryFormatter()
            b.Serialize(s, list)
            s.Close()
        End Sub
    End Class
    Sub Main()
        Dim SerSample As Ser = New Ser()
        With SerSample
            .Scope1()
            .Scope2()
            .Scope3()
            .Scope4()
        End With
    End Sub
End Module