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Hi,
I recently started using VB2005 and i find it very confusing, in VB6 i used to unload form using UNLOAD ME but it doesn't work in 2005, plus i tried Me.Close() and Me.Dispose() as well but it closes my application, rather than form.
Here's the code i'm working on.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click<br />
Dim usname As String<br />
usname = StrConv(TextBox1.Text, VbStrConv.ProperCase)<br />
If usname = "Admin" And TextBox2.Text = "pass" Then<br />
MsgBox("Welcome to Form two", MsgBoxStyle.Information + MsgBoxStyle.OkOnly)<br />
Me.Close()<br />
Form2.Show()<br />
Else<br />
MsgBox("Wrong Login details", MsgBoxStyle.Exclamation + MsgBoxStyle.RetryCancel)<br />
If MsgBoxResult.Retry Then<br />
TextBox1.Text = ""<br />
TextBox2.Text = ""<br />
TextBox1.Focus()<br />
ElseIf MsgBoxResult.Cancel Then<br />
End<br />
End If<br />
End If<br />
End Sub
can someone please help me out with this...
Thanks.
Parth Patel
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VB6 taught you some bad habits you have to break.
In VB6, all forms exist all the time. Under true OOP and VB.NET 2005, this is not the case. A form doesn't exist until your code creates an instance of it and shows it. Your code is then responsible for disposing of it when you're done with it. Forms are classes, just like any other class in the .NET Framework you create an instance of.
Putting a Me.Close in your startup form will close your entire application because you just killed off the form that's holding your application's message pump. A form should not kill itself off. The code that created and launched it normally would do this.
You cannot transfer control from one form to another like you're trying to do. Forms get created and destroyed in a tree-like fashion. Form1 creates Form2 and shows it, which may create Form3 and show it, which may create forms 4, 5, and 6. If the instance of Form2 dies, all the forms that it created and launched, and their child forms, die along with it.
The only thing you can do to not show your Form1 and give the illusion that Form2 is now the main form is to Me.Hide().
In the case of a login form, there's a few different ways to do this. The first is to have a Sub Main launch the puts up a form and lets it check the credentials, then returns the login state to Main. Based on that result, Main then created a second form that is the main application form.
<STAThread()> _
Shared Sub Main()
Using loginForm As New MyLoginForm
Application.Run(loginForm)
If loginForm.DialogResult = Windows.Forms.DialogResult.OK Then
If loginForm.LoginSuccessful Then
Application.Run(New MyMainForm)
End If
End If
End Using
End Sub
Of course, LoginSuccessfulwould probably be a public property on the login form that this code checks to see if the credentials were good. It would probably also expose the credentials or some role information as a public property too.
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Dave Kreskowiak wrote: <stathread()> _
Shared Sub Main()
Using loginForm As New MyLoginForm
Application.Run(loginForm)
If loginForm.DialogResult = Windows.Forms.DialogResult.OK Then
If loginForm.LoginSuccessful Then
Application.Run(New MyMainForm)
End If
End If
End Using
End Sub
Thank you very much for your help, but can you please tell me where do i put this code. I'm student learning so i don't really know much about Visual Basic.
Thanks
Parth Patel
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Either in a Module (yuk!) or in your startup form's code. Then you go into your project properties and change the Startup item to Sub Main.
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hi there,
can someone help me on how will i pass or copy (programmatically) the information inside or declared on the datagridview1 to datagridview2.
It's like on text box.. textbox1.text = textbox2.text
i just want the datagridview2 to have the data inside the datagridview1(through a mouse click) but without the use of any dataset coz it's not binded with the sql database.
can you show me codes.
i really can't figure it out eh..
thank you so much..;)
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without trying it:
datagridview2.datasource = datagridview1.datasource
datagridview2.datamember = datagridview1.datamember
datagridview2.refresh
???
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this is just what i need..
I tried to use this codes and it works, with the use of some codes such as the declaration of the datatable columns.
thanks a lot..
this really helped me.
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I have many forms in my application but I am not able to close last Form just after shited to the another Form(eg I'm in Form1 and click on button to go to another Form then the Form2 will open successfully but previous Form (Form1) also open in the background).
Pls suggest me what should I do?
regards
Praveen
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There are many ways of doing it.
1. Form.Visible = Fale ' this will hide your form in any Visual Basic Version
2. Unload Form ' this is only for VB6. this will unload your form
3. Form.Close()
4. Form.Dispose()
No. 3 & 4 works with VB2005
And ye Use ME insted of form, because sometimes form might give u error.
Post back if u have anymore questions.
Parth Patel
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Hi guys,
Just want to ask anyone who knows how to use a graph in vb.net? i haven't used a component ever since so i'm really new at this.
i have a component in vb.net called Microsoft Chart. i just don't know how to work on it.
if you can tell me a tutorial site, please do. I just badly need it.
or does anybody know any other components that i can use for charting?
i also need some sample codes to study on how to adjust the bargraph stats programmatically. Can you give me?
Hope you guys would help me.
Thank you.
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Hey
You may want to look at simpler components first, is there no documentation on your chart component on www.msdn.com?
Maybe try some general VB tutorials first http://www.homeandlearn.co.uk/NET/vbNet.html - my apologies if these seem too simple but I dont know what standard you are at. Also try amazon for books on VB.NET - better to walk before you run.
Dan
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ok, I'll take your advice.
Thank you so much..
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I have an owner-owned pair of forms and I'd like to raise events from one to the other. I can't seem to find it in the big tome I use. Any ideas?
Richard H.
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without better specefied what you have and what you want I can only tell you this:
declare a public event in the owned form
lets call it
public event bla
then when you need to catch the event (in the owner form)
say when a button is cliced on the owned form put
raisevent bla in the buttonclick event
then in the owner form you should be able to add a handler to the event bla
dim frm as ownedfrom
addhandler frm.bla, addressof blabla
private sub blabla (sender as object,e as system.eventargs)
'do you're code here
end sub
hope it helps
ps: sorry about the poor naming but it's been a long day (really need to get some sleep  )
If my help was helpfull let me know, if not let me know why.
The only way we learn is by making mistaks.
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A better choice would be a delegate but here's how you'd do it...
Class Form1
private withevents moForm2 as Form2
Private sub Form1_Load(sender as object, e as system.eventargs) handles Form1.Load
moForm2 = New Form2
End Sub
private sub moForm2_Selection(sDate as String) handles moForm2.Selection
'do whatever you want
End Sub
End Class
Class Form2
Event Selection(sDate as String)
Private Sub Test()
RaiseEvent Selection("09/19/2007")
End Sub
End Class
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You guys got me started, thanks. It was a custom event from an "owner" form to its "owned" form. I tried several ways, unsuccessfully. It wasn't until I declared the event as Shared in the owner form that everything fell into place nicely.
Thanks for your help.
Richard H.
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Hi
I'm currently working on a program for automated print queue creation (move, copy, clone). Creating a print queue with AddPrinter on remote server works, but I can't figure out how to apply the DEVMODE. The code works as follows:
-using OpenPrinter to get the handle to the printer on the source server
-query printer with GetPrinter to get Printer_Info_2 and DEVMODE structure
-changing the needed values in the Printer_Info_2 and DEVMODE structure
-using AddPrinter to create the printer on the destination server
now I want to set the "Document Defaults" (like Collate or Orientation), but the API call DocumentProperties fails....
Public Function fMovePrinter( _<br />
<br />
ByVal sSource As String, _<br />
<br />
ByVal sDestination As String, _<br />
<br />
ByVal sPrinter As String, _<br />
<br />
ByVal lvSource As ListView, _<br />
<br />
ByVal lvDestination As ListView, _<br />
<br />
ByVal bDelete As Boolean _<br />
<br />
) As Boolean<br />
<br />
'first open the source printer to get the handle<br />
<br />
Dim hSource As IntPtr<br />
<br />
Dim pd As New PRINTER_DEFAULTS<br />
<br />
pd.DesiredAccess = PrinterAccessRights.PRINTER_ALL_ACCESS<br />
<br />
If Not OpenPrinter(sPrinter, hSource, pd) Then<br />
<br />
Throw New Exception(Err.LastDllError & " unable to OpenPrinter " & sPrinter)<br />
<br />
Return False<br />
<br />
End If<br />
<br />
'now call the GetPrinter API to get the PRINTER_INFO_2 structure<br />
<br />
Dim BytesWritten As Int32 = 0<br />
<br />
Dim ptBuf As IntPtr<br />
<br />
Dim pi2 As New PRINTER_INFO_2<br />
<br />
Dim dmOut As New DEVMODE<br />
<br />
ptBuf = Marshal.AllocHGlobal(1)<br />
<br />
'Get the number of bytes needed<br />
<br />
If Not GetPrinter(hSource, 2, ptBuf, 1, BytesWritten) Then<br />
<br />
If BytesWritten > 0 Then<br />
<br />
Marshal.FreeHGlobal(ptBuf)<br />
<br />
ptBuf = Marshal.AllocHGlobal(BytesWritten)<br />
<br />
'Get the PRINTER_INFO_2 structure<br />
<br />
If GetPrinter(hSource, 2, ptBuf, BytesWritten, BytesWritten) Then<br />
<br />
Marshal.PtrToStructure(ptBuf, pi2)<br />
<br />
If pi2.lpDeviceMode > 0 Then<br />
<br />
'Get the DEVMODE structure<br />
<br />
Dim ptrDevMode As New IntPtr(pi2.lpDeviceMode)<br />
<br />
Marshal.PtrToStructure(ptrDevMode, dmOut)<br />
<br />
End If<br />
<br />
Else<br />
<br />
Marshal.FreeHGlobal(ptBuf)<br />
<br />
ClosePrinter(hSource)<br />
<br />
Throw New Exception(Err.LastDllError & " unable to GetPrinter #2 " & sPrinter)<br />
<br />
Return False<br />
<br />
End If<br />
<br />
'free ptBuf<br />
<br />
Marshal.FreeHGlobal(ptBuf)<br />
<br />
ClosePrinter(hSource)<br />
<br />
Else<br />
<br />
Throw New Exception(Err.LastDllError & " BytesWritten " & BytesWritten)<br />
<br />
Return False<br />
<br />
End If<br />
<br />
Else<br />
<br />
Throw New Exception(Err.LastDllError & " unable to GetPrinter #1 " & sPrinter)<br />
<br />
Return False<br />
<br />
End If<br />
<br />
'modify the pi2 structure with the needed parameters<br />
<br />
Dim strPrinter As String<br />
<br />
strPrinter = sPrinter<br />
<br />
If strPrinter.LastIndexOf("\") > 0 Then<br />
<br />
strPrinter = strPrinter.Remove(strPrinter.IndexOf("\"), strPrinter.LastIndexOf("\") + 1)<br />
<br />
End If<br />
<br />
With pi2<br />
<br />
.pPrinterName = strPrinter<br />
<br />
.pServerName = sDestination<br />
<br />
.pPortName = "LPT1:"<br />
<br />
End With<br />
<br />
'change the DEVMODE structure with the needed parameters<br />
<br />
With dmOut<br />
<br />
.pDeviceName = "\\" & sDestination & "\" & strPrinter<br />
<br />
End With<br />
<br />
'copy the devmode structure back into the PRINTER_INFO_2 structure<br />
<br />
'Dim hdmIn As IntPtr<br />
<br />
pi2.lpDeviceMode = Marshal.AllocHGlobal(Marshal.SizeOf(dmOut))<br />
<br />
Marshal.StructureToPtr(dmOut, pi2.lpDeviceMode, False)<br />
<br />
<br />
<br />
'create the printer on the destination<br />
<br />
Dim hDestination As IntPtr<br />
<br />
hDestination = AddPrinter("\\" & sDestination, 2, pi2)<br />
<br />
If hDestination = 0 Then<br />
<br />
Throw New Exception(Err.LastDllError & " unable to AddPrinter")<br />
<br />
Return False<br />
<br />
End If<br />
<br />
Dim intRet As Int32<br />
<br />
intRet = DocumentProperties(IntPtr.Zero, hDestination, strPrinter, pi2.lpDeviceMode, pi2.lpDeviceMode, DocumentPropertiesModes.DM_IN_BUFFER Or DocumentPropertiesModes.DM_OUT_BUFFER)<br />
<br />
Debug.Print(Err.LastDllError)<br />
<br />
Return True<br />
<br />
<br />
<br />
<br />
<br />
End Function<br />
<br />
<br />
<br />
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Public Function fMovePrinter( _<br />
ByVal sSource As String, _<br />
ByVal sDestination As String, _<br />
ByVal sPrinter As String, _<br />
ByVal lvSource As ListView, _<br />
ByVal lvDestination As ListView, _<br />
ByVal bDelete As Boolean _<br />
) As Boolean<br />
<br />
'first open the source printer to get the handle<br />
Dim hSource As IntPtr<br />
Dim pd As New PRINTER_DEFAULTS<br />
<br />
pd.DesiredAccess = PrinterAccessRights.PRINTER_ALL_ACCESS<br />
If Not OpenPrinter(sPrinter, hSource, pd) Then<br />
Throw New Exception(Err.LastDllError & " unable to OpenPrinter " & sPrinter)<br />
Return False<br />
End If<br />
<br />
'now call the GetPrinter API to get the PRINTER_INFO_2 structure<br />
Dim BytesWritten As Int32 = 0<br />
Dim ptBuf As IntPtr<br />
Dim pi2 As New PRINTER_INFO_2<br />
Dim dmOut As New DEVMODE<br />
<br />
ptBuf = Marshal.AllocHGlobal(1)<br />
<br />
'Get the number of bytes needed<br />
If Not GetPrinter(hSource, 2, ptBuf, 1, BytesWritten) Then<br />
If BytesWritten > 0 Then<br />
Marshal.FreeHGlobal(ptBuf)<br />
ptBuf = Marshal.AllocHGlobal(BytesWritten)<br />
'Get the PRINTER_INFO_2 structure<br />
If GetPrinter(hSource, 2, ptBuf, BytesWritten, BytesWritten) Then<br />
Marshal.PtrToStructure(ptBuf, pi2)<br />
If pi2.lpDeviceMode > 0 Then<br />
'Get the DEVMODE structure<br />
Dim ptrDevMode As New IntPtr(pi2.lpDeviceMode)<br />
Marshal.PtrToStructure(ptrDevMode, dmOut)<br />
End If<br />
Else<br />
Marshal.FreeHGlobal(ptBuf)<br />
ClosePrinter(hSource)<br />
Throw New Exception(Err.LastDllError & " unable to GetPrinter #2 " & sPrinter)<br />
Return False<br />
End If<br />
'free ptBuf<br />
Marshal.FreeHGlobal(ptBuf)<br />
'ClosePrinter(hSource)<br />
Else<br />
Throw New Exception(Err.LastDllError & " BytesWritten #1 " & BytesWritten)<br />
Return False<br />
End If<br />
<br />
Else<br />
Throw New Exception(Err.LastDllError & " unable to GetPrinter #1 " & sPrinter)<br />
Return False<br />
End If<br />
<br />
'modify the pi2 structure with the needed parameters<br />
Dim strPrinter As String<br />
strPrinter = sPrinter<br />
If strPrinter.LastIndexOf("\") > 0 Then<br />
strPrinter = strPrinter.Remove(strPrinter.IndexOf("\"), strPrinter.LastIndexOf("\") + 1)<br />
End If<br />
<br />
With pi2<br />
.pPrinterName = strPrinter<br />
.pServerName = sDestination<br />
.pPortName = "LPT1:"<br />
End With<br />
<br />
'change the DEVMODE structure with the needed parameters<br />
Dim strFullPrinterPath As String = "\\" & sDestination & "\" & strPrinter<br />
With dmOut<br />
.pDeviceName = strFullPrinterPath<br />
End With<br />
<br />
'copy the devmode structure back into the PRINTER_INFO_2 structure<br />
'Dim hdmIn As IntPtr<br />
pi2.lpDeviceMode = Marshal.AllocHGlobal(Marshal.SizeOf(dmOut))<br />
Marshal.StructureToPtr(dmOut, pi2.lpDeviceMode, False)<br />
<br />
If bDelete = True Then<br />
Call DeletePrinter(hSource)<br />
hSource = IntPtr.Zero<br />
End If<br />
<br />
'create the printer on the destination<br />
Dim hDestination As IntPtr<br />
hDestination = AddPrinter("\\" & sDestination, 2, pi2)<br />
If hDestination = 0 Then<br />
If Err.LastDllError = 1802 Then<br />
Call DeletePrinter(hSource)<br />
Debug.Print(Err.LastDllError.ToString)<br />
hDestination = AddPrinter("\\" & sDestination, 2, pi2)<br />
If hDestination = 0 Then<br />
Throw New Exception(Err.LastDllError & " unable to AddPrinter, tried twice because printer allready exists on " & sDestination)<br />
Return False<br />
End If<br />
Else<br />
Throw New Exception(Err.LastDllError & " unable to AddPrinter")<br />
Return False<br />
End If<br />
End If<br />
<br />
If hSource <> 0 Then<br />
ClosePrinter(hSource)<br />
hSource = IntPtr.Zero<br />
End If<br />
<br />
'dmOut = Nothing<br />
<br />
Dim intRet As Int32<br />
'get size of the DEVMODE structure<br />
intRet = DocumentProperties(IntPtr.Zero, hDestination, strFullPrinterPath, IntPtr.Zero, IntPtr.Zero, DocumentPropertiesModes.DM_GETSIZE)<br />
If intRet < 0 Then<br />
Throw New Exception(Err.LastDllError & " unable to get DocumentProperties #1")<br />
Return False<br />
End If<br />
<br />
'create a new instance of the DEVMODE structure with size returned<br />
Dim hdmIn As IntPtr<br />
hdmIn = Marshal.AllocHGlobal(intRet)<br />
<br />
intRet = DocumentProperties(IntPtr.Zero, hDestination, strFullPrinterPath, hdmIn, IntPtr.Zero, DocumentPropertiesModes.DM_OUT_BUFFER)<br />
If intRet < 0 Then<br />
Throw New Exception(Err.LastDllError & " unable to get DocumentProperties #2")<br />
Return False<br />
End If<br />
<br />
'get the structure from the pointer<br />
Dim dmIn As New DEVMODE<br />
dmIn = Marshal.PtrToStructure(hdmIn, dmIn.GetType)<br />
<br />
'modify the structure with the settings from the source printer<br />
With dmIn<br />
.dmCollate = dmOut.dmCollate<br />
.dmColor = dmOut.dmColor<br />
.dmCopies = dmOut.dmCopies<br />
.dmDefaultSource = dmOut.dmDefaultSource<br />
.dmDuplex = dmOut.dmDuplex<br />
.dmFormName = dmOut.dmFormName<br />
.dmMediaType = dmOut.dmMediaType<br />
.dmOrientation = dmOut.dmOrientation<br />
.dmPaperLength = dmOut.dmPaperLength<br />
.dmPaperSize = dmOut.dmPaperSize<br />
.dmPaperWidth = dmOut.dmPaperWidth<br />
.dmPrintQuality = dmOut.dmPrintQuality<br />
.dmScale = dmOut.dmScale<br />
.dmSize = dmOut.dmSize<br />
.dmTTOption = dmOut.dmTTOption<br />
End With<br />
<br />
'copy the structure back in the pointer<br />
Marshal.StructureToPtr(dmIn, hdmIn, False)<br />
<br />
'set the new settings on the destination printer<br />
intRet = DocumentProperties(IntPtr.Zero, hDestination, strFullPrinterPath, hdmIn, hdmIn, DocumentPropertiesModes.DM_IN_BUFFER Or DocumentPropertiesModes.DM_OUT_BUFFER)<br />
If intRet < 0 Then<br />
Throw New Exception(Err.LastDllError & " unable to set DocumentProperties #1")<br />
Return False<br />
End If<br />
<br />
'reget the PRINTER_INFO_2 structure from the destination printer<br />
Dim PI2In As New PRINTER_INFO_2<br />
'Dim hPI2In As IntPtr<br />
BytesWritten = 0<br />
ptBuf = Marshal.AllocHGlobal(1)<br />
If Not GetPrinter(hDestination, 2, ptBuf, 1, BytesWritten) Then<br />
If BytesWritten > 0 Then<br />
Marshal.FreeHGlobal(ptBuf)<br />
ptBuf = Marshal.AllocHGlobal(BytesWritten)<br />
'reget the PRINTER_INFO_2 structure<br />
If GetPrinter(hDestination, 2, ptBuf, BytesWritten, BytesWritten) Then<br />
Marshal.PtrToStructure(ptBuf, PI2In)<br />
PI2In.lpDeviceMode = hdmIn<br />
'hPI2In = Marshal.AllocHGlobal(Marshal.SizeOf(PI2In))<br />
'Marshal.StructureToPtr(PI2In, hPI2In, False)<br />
intRet = SetPrinter(hDestination, 2, PI2In, PrinterControlCommands.PRINTER_CONTROL_SETPRINTERINFO)<br />
Debug.Print(Err.LastDllError)<br />
If intRet = 0 Then<br />
Throw New Exception(Err.LastDllError & " unable to SetPrinter #1")<br />
Return False<br />
End If<br />
Else<br />
Marshal.FreeHGlobal(ptBuf)<br />
ClosePrinter(hDestination)<br />
Throw New Exception(Err.LastDllError & " unable to GetPrinter #3 " & strFullPrinterPath)<br />
Return False<br />
End If<br />
Else<br />
Throw New Exception(Err.LastDllError & " BytesWritten #2 " & BytesWritten)<br />
Return False<br />
End If<br />
End If<br />
Call ClosePrinter(hDestination)<br />
Marshal.FreeHGlobal(hdmIn)<br />
Dim lvItem As New ListViewItem<br />
lvItem = lvDestination.Items.Add(sPrinter)<br />
lvItem.SubItems.Add(PI2In.pDriverName)<br />
lvItem.SubItems.Add(PI2In.pShareName)<br />
lvDestination.Refresh()<br />
Me.Refresh()<br />
pi2 = Nothing<br />
PI2In = Nothing<br />
dmIn = Nothing<br />
dmOut = Nothing<br />
Return True<br />
End Function
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can someone help me..
how can you make a report using crystal report and the source is from the datagridview.. i need to have a printable copy of the data in the datagridview..
pls help...
gt
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can pls someone help me how to save all items in a listview to the database....
pls help...
gt
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Pretty vague question  you can reply being more specific. The vague answer is to iterate through the items in the listview, and insert them into your DB item by item
I get all the news I need from the weather report - Paul Simon (from "The Only Living Boy in New York")
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I want retive system of time.how to get it?
thank you
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I googled "vb.net get time"
Here is the what I found on the third line:
<br />
Dim Now AsDateTime = DateTime.Now<br />
MessageBox.Show(Now)<br />
You always pass failure on the way to success.
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