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Subject:
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vb 2003 to 2005 convert gone wrong
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Posted By:
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mr_kane
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Post Date:
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8/5/2007 12:19:12 PM
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I have a program that used to work with my old version of visual studio but now i have upgraded to 2005 and Vista, but the programs stopped working.
The error i am getting is:
System.InvalidCastException was unhandled Conversion from string "" to type 'Boolean' is not valid.
Here's the code
Public Class Form1
Inherits System.Windows.Forms.Form
#Region " Windows Form Designer generated code "
Public Sub New()
MyBase.New()
'This call is required by the Windows Form Designer.
InitializeComponent()
'Add any initialization after the InitializeComponent() call
End Sub
'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
Friend WithEvents btnMain As System.Windows.Forms.Button
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.btnMain = New System.Windows.Forms.Button
Me.SuspendLayout()
'
'btnMain
'
Me.btnMain.Location = New System.Drawing.Point(24, 16)
Me.btnMain.Name = "btnMain"
Me.btnMain.Size = New System.Drawing.Size(240, 23)
Me.btnMain.TabIndex = 0
Me.btnMain.Text = "Give me my Task Manager beee-ach"
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(292, 54)
Me.Controls.Add(Me.btnMain)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
#End Region
Private Sub btnMain_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMain.Click
'read registry
If CBool(ReadWriteCURegistry("Software\Microsoft\Windows\CurrentVersion\Policies\System", "DisableTaskMgr", False)) = False Then
'change registry
ReadWriteCURegistry("Software\Microsoft\Windows\CurrentVersion\Policies\System", "DisableTaskMgr", True, "1")
btnMain.Text = "Enable task manager"
Else
ReadWriteCURegistry("Software\Microsoft\Windows\CurrentVersion\Policies\System", "DisableTaskMgr", True, "00")
btnMain.Text = "Disable task manager"
End If
End Sub
Private Function ReadWriteCURegistry(ByVal subkey As String, Optional ByVal value As String = "", Optional ByVal openToWrite As Boolean = False, Optional ByVal writetokey As String = "") As String
Dim regKey As Microsoft.Win32.RegistryKey
Dim key As Boolean
Try
regKey = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(subkey, openToWrite)
If openToWrite Then
regKey.SetValue(value, writetokey)
End If
key = regKey.GetValue(value)
regKey.Close()
Return key
Catch ex As Exception
Return Nothing
End Try
End Function
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
If CBool(ReadWriteCURegistry("Software\Microsoft\Windows\CurrentVersion\Policies\System", "DisableTaskMgr", False)) = False Then
btnMain.Text = "Disable task manager"
Else
btnMain.Text = "Enable task manager"
End If
End Sub
End Class
I am getting this error on this line:
If CBool(ReadWriteCURegistry("Software\Microsoft\Windows\CurrentVersion\Policies\System", "DisableTaskMgr", False)) = False Then
I'm unsure how to deal with the issue, i've heard about the convert class but don't think i can use this here. Any help is greatly accepted.
Kane
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Reply By:
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Imar
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Reply Date:
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8/5/2007 2:14:13 PM
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Hi there,
You may want to set Option Explicit and Option Strict on to have the compiler tell you about these problems at compile time. Take a look at this:
Private Function ReadWriteCURegistry(ByVal subkey As String,
Optional ByVal value As String = "", Optional ByVal openToWrite As
Boolean = False, Optional ByVal writetokey As String = "") As String
Dim key As Boolean
End Function
You declare the method as a String, yet to have it return a Boolean and finally you treat the result as a Boolean. Why not declare the method as a Boolean method?
Private Function ReadWriteCURegistry(ByVal subkey As String,
Optional ByVal value As String = "", Optional ByVal openToWrite As
Boolean = False, Optional ByVal writetokey As String = "") As Boolean
Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
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Reply By:
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mr_kane
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Reply Date:
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8/5/2007 4:35:08 PM
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Many thanks Imar, i can't believe it was that simple.
Kane 
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