VB.Net Tutorial/Data Type/CType — различия между версиями

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м (1 версия)
 
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Текущая версия на 15:54, 26 мая 2010

Use CType to convert from derived class to base class

<source lang="vbnet">public class Test

  public Shared Sub Main
       Dim people As New Collection
       people.Add(New Employee("A"))
       people.Add(New Customer("B"))
       Dim emp As Employee
       For Each person As Object In people
           If TypeOf person Is Employee Then
               emp = CType(person, Employee)
               Console.WriteLine(emp.Name)
           ElseIf TypeOf person Is Customer Then
               Console.WriteLine(CType(person, Customer).Name)
           End If
       Next person
  End Sub

End class

Public Class Employee

   Public Name As String
   Public Sub New(ByVal new_name As String)
       Name = new_name
   End Sub
   Public Overridable Function IsManager() As Boolean
       Return False
   End Function

End Class Public Class Customer

   Public Name As String
   Public Sub New(ByVal new_name As String)
       Name = new_name
   End Sub

End Class Public Class Manager

   Inherits Employee
   Public Sub New(ByVal new_name As String)
       MyBase.new(new_name)
   End Sub
   Public Overrides Function IsManager() As Boolean
       Return True
   End Function

End Class</source>

A
B