Public Class Credit_Account
 
    Private AccountName As String       'Customer's Account Name
    Private AccountNumber As Integer   'Customer's Account Number
    Protected Balance As Double         'Customer's Account Balance
 
    Public Sub New(ByVal Nm As String, ByVal Bal As Double)
        AccountName = Nm
        Balance = Bal
    End Sub
 
    Property AccName() As String
        Get
            Return AccountName
        End Get
        Set(ByVal Value As String)
            AccountName = Value
        End Set
    End Property
 
    Property AccNumber() As Integer
        Get
            Return AccountNumber
        End Get
        Set(ByVal Value As Integer)
            AccountNumber = Value
        End Set
    End Property
 
    ReadOnly Property AccountBal() As Double
        Get
            Return Balance
        End Get
    End Property
 
    Public Overridable Sub Deposit(ByVal Amount As Double)
        Balance += Amount
    End Sub
 
    Public Overridable Sub Withdraw(ByVal Amount As Double)
        Balance -= Amount
    End Sub
    Public Overridable Sub Display()
        Console.WriteLine("Name=" & AccountName & ", " & "Balance=" & Balance)
    End Sub
 
    Public Sub ChangeName(ByVal newName As String)
        AccountName = newName
    End Sub
    ' Initial balance is zero for each new instance
    Public Sub New()
        Balance = 0
    End Sub
End Class

Public Class Saving_Account
    Inherits Credit_Account
 
    Public Sub New(ByVal Nm As String, _
                       ByVal Bal As Double)
 
        MyBase.New(Nm, Bal)
 
    End Sub
    Public Overrides Sub Withdraw(ByVal Amount As Double)
        If Amount <= Balance Then  ' Use balance, inherited from base class
            MyBase.Withdraw(Amount)    ' Call Withdraw, inherited from base class
        End If
    End Sub
 
    Public Overrides Sub Display()
        MyBase.Display()           ' Call Display, inherited from base class
        Console.WriteLine("There are insufficient funds to complete this transaction." & vbCrLf _
        & "This account cannot have a negative balance.", "Transaction Error")
    End Sub
End Class