活代码LINQ——05

片段代码：

' Exercise 9.3  Solution: Invoice.vb
' Invoice class.
Public Class invoide ' declare variables for Invoice object
    Private partNumberValue As Integer
    Private partDescriptionValue As String
    Private quantityValue As Integer
    Private priceValue As Decimal   ' four-argument constructor

    Public Sub New(ByVal part As Integer, ByVal description As String, ByVal count As Integer, ByVal pricePerItem As Decimal)
        PartNumber = part
        PartDescription = description
        Quantity = count
        Price = pricePerItem
    End Sub ' New

    ' property for partNumberValue; no validation necessary
    Public Property PartNumber() As Integer
        Get
            Return partNumberValue
        End Get

        Set(ByVal value As Integer)
            partNumberValue = value
        End Set
    End Property ' PartNumber

    ' property for partDescriptionValue; no validation necessary
    Public Property PartDescription() As String
        Get
            Return partDescriptionValue
        End Get

        Set(ByVal value As String)
            partDescriptionValue = value
        End Set
    End Property ' PartDescription

    ' property for quantityValue; ensures value is positive
    Public Property Quantity() As Integer
        Get
            Return quantityValue
        End Get

        Set(ByVal value As Integer)
            If value > 0 Then ' determine whether quantity is positive
                quantityValue = value ' valid quantity assigned
            End If
        End Set
    End Property ' Quantity

    ' property for pricePerItemValue; ensures value is positive
    Public Property Price() As Decimal
        Get
            Return priceValue
        End Get

        Set(ByVal value As Decimal)
            If value > 0 Then ' determine whether price is positive
                priceValue = value ' valid price assigned
            End If
        End Set
    End Property ' Price

    ' return String containing the fields in the Invoice in a nice format
    Public Overrides Function ToString() As String
        ' left justify each field, and give large enough spaces so  all the columns line up
        Return String.Format("{0,-5} {1,-20} {2,-5} {3,6:C}", PartNumber, PartDescription, Quantity, Price)
    End Function ' ToString
End Class ' Invoice

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源于：visual basic 2008 how to program