VB.Net/Class/Instance Variables — различия между версиями
Admin (обсуждение | вклад) м (1 версия) |
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Текущая версия на 12:42, 26 мая 2010
Scope rules and instance variables
Imports System
Public Class MainClass
" instance variable can be used anywhere in class
Shared Dim value As Integer = 1
Shared Sub Main(ByVal args As String())
" variable local to FrmScoping_Load hides instance variable
Dim value As Integer = 5
Console.WriteLine( "local variable value in" & _
" FrmScoping_Load is " & value )
MethodA() " MethodA has automatic local value
MethodB() " MethodB uses instance variable value
MethodA() " MethodA creates new automatic local value
MethodB() " instance variable value retains its value
Console.WriteLine( vbCrLf & vbCrLf & "local variable " & _
"value in FrmScoping_Load is " & value )
End Sub
" automatic local variable value hides instance variable
Shared Sub MethodA()
Dim value As Integer = 25 " initialized after each call
Console.WriteLine( vbCrLf & vbCrLf & "local variable " & _
"value in MethodA is " & value & " after entering MethodA" )
value += 1
Console.WriteLine( vbCrLf & "local variable " & _
"value in MethodA is " & value & " before exiting MethodA" )
End Sub " MethodA
" uses instance variable value
Shared Sub MethodB()
Console.WriteLine( vbCrLf & vbCrLf & "instance variable" & _
" value is " & value & " after entering MethodB" )
value *= 10
Console.WriteLine( vbCrLf & "instance variable " & _
"value is " & value & " before exiting MethodB" )
End Sub " MethodB
End Class