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shiroamachi wrote: how about connection and recordset object? Do we need to call the close method and set the object to nothing?
You absolutely must Close them. You do not have to set them to Nothing. They'll be removed from memory as soon as they go out of scope.
shiroamachi wrote: When to call open and close method of connection and recordset object in a procedure/function with try catch? Is it ok to put in "finally" ?
Uhhh... VB6 doesn't have try/catch functionality. Sounds like you're talking about VB.NET. If you are, then Finally is a good place to call Close.
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my bad. topic starter talking about VB6. I'm asking about VB.Net
is there a way to check a recordset is open or not ?
here's a case
try<br />
dim con as connection<br />
dim rs as recordset<br />
con.open()<br />
rs = con.execute(sqlstring)<br />
<br />
catch ex as Exception<br />
<br />
msgbox "error"<br />
exit sub<br />
<br />
finally<br />
<br />
rs.close()<br />
con.close()<br />
<br />
end try
assume there's error in con.open() and the error was catch and then do finally. in finally, because of rs is not yet open, will cause error cant close object that isnt open. How to resolve this problem?
Thank
WiL
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shiroamachi wrote: assume there's error in con.open() and the error was catch and then do finally. in finally, because of rs is not yet open, will cause error cant close object that isnt open. How to resolve this problem?
First, put the DIM statements before the Try since the variables won't have scope outside the Try block.
Second, in the Catch block determine whether or not the Connection object is open by using something like this:
if con.State = adStateOpen then
con.Close()
end if
I did this from memory so you'll need to check the exact syntax.
...Steve
"Give a man a fish and you've fed him for a day. Teach him how to fish and you've fed him for life." (Translation: I'll show you the way, but not write the code for you.) I read that somewhere once 
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I believe the "adStateOpen" constant is from VB6's ADO.
In ADO.NET it should be like this...
If (con.State <> ConnectionState.Closed) Then
con.Close()
End If
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I am using a windows form datagrid and a datatable is used as the datasource.I want to prevent deletion of the first row.I tried with datatable's rowdeleting event.But i was not able to reject the changes.Can any one help.I'm pasting the code that i tried
Private Sub DataTable_RowDeleting(ByVal sender As System.Object, ByVal e As System.Data.DataRowChangeEventArgs)
If e.Action = DataRowAction.Delete Then
If dgGrid.CurrentCell.RowNumber = 0 Then
e.Row.RejectChanges()
CType(sender, DataTable).AcceptChanges()
End If
Else
e.Row.AcceptChanges()
End If
End Sub
Anup
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can I upload data to a server from a vb.net windows-app? I know how to upload but I don't know how to LOG into my ftp server to upload file. please it's important
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ok.I found the solution.bye
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Hello All
I want to manually enter items in the combox as:
cbo.Items.Add("Item1")
cbo.Items.Add("Item2")
How i can add ValueMember Field data manually? As we have an option in VB6 as:
cbo.AddItem ("Item1")
cbo.ItemData(cbo.NewIndex) = 1 'How this can be done in VB.Net? 
cbo.AddItem ("Item2")
cbo.ItemData(cbo.NewIndex) = 2 'How this can be done in VB.Net?
Regards
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How to open the start menu on the desktop and the windows task manager.
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confusing,
make your question clear.
openning with vb or not.
to open taskmgr you can use shell("taskmgr.exe") otherwise press CTRL+ALT+DEL
Kanchana
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You're looking for the Shell Automation object. Add a reference to the Shell32.dll, usually found in C:\Windows\System32. In your code, you do something like this:
Imports Shell32
.
.
.
Public Class Form1
Private Sub Button1_Click(blah, blah) Handles Button1.Click
Dim myShellObject As New Shell32.Shell
myShellObject.Open(ShellSpecialFolderConstants.ssfDRIVES)
End Sub
End Class
You can find out what all the special folder constants refer to here[^] on MSDN.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Hi,
I want to integrate my webbased or VB applications to a Label Printer for printing the Employees Address alone. Pls Can anyone help me to how to acheive this..Pls help
Thanks In Advance
Ram
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A label printer is no different than an inkjet or laser printer. The paper is just a lot smaller. What part of this are you having a problem with?
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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i want to connect a lamp to my pc via com1 or any ports and write a simple code using vb.net to control on/off???
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I assume your talking about an LED and not a 110/220V light bulb!
First, the serial port is a bad choice to connect an LED to. It's cumbersome to control since most signals only last a fraction of a second on the serial port and there are only a few lines that will actually hold a signal up or down. The better choice for this would be the Parallel port. You can find many exmaples of this on the web.
A good example, complete with LED's and switch inputs, can be found at http://www.logix4u.net[^]
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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<br />
Friend Sub renderPicture()<br />
Dim previewFile, tempPreviewFile As String<br />
Dim numberOfSelectedItem As Integer<br />
Dim bitmapSource As Bitmap<br />
Dim graphicDestination As Graphics<br />
Dim selectedFileName As String<br />
Dim scale As Single<br />
<br />
If Not picPreview.Image Is Nothing Then<br />
picPreview.Image.Dispose()<br />
End If<br />
<br />
If Not bitmapDestination Is Nothing Then<br />
bitmapDestination.Dispose()<br />
End If<br />
<br />
numberOfSelectedItem = lstFiles.SelectedItems.Count<br />
<br />
If numberOfSelectedItem > 0 Then<br />
Dim dummy = lstFiles.SelectedItems.Item(numberOfSelectedItem - 1)<br />
previewFile = UCase(previewCachePath).Replace("SCANNED FILES", "SCANNE~1") & Mid(dummy, 1, Len(dummy) - 4) & "001.png"<br />
tempPreviewFile = UCase(previewCachePath).Replace("SCANNED FILES", "SCANNE~1") & Mid(dummy, 1, Len(dummy) - 4) & "[t].png"<br />
If System.IO.File.Exists(previewFile) Then<br />
If Not System.IO.File.Exists(tempPreviewFile) Then<br />
System.IO.File.Copy(previewFile, tempPreviewFile)<br />
End If<br />
End If<br />
<br />
Try<br />
bitmapSource = New Bitmap(Bitmap.FromFile(tempPreviewFile))<br />
Catch ex As Exception<br />
Module1.setErrMsg(ex.Message)<br />
Exit Sub<br />
End Try<br />
Select Case cmbZoom.Text<br />
Case "150%"<br />
scale = CSng(1.5)<br />
Case "125%"<br />
scale = CSng(1.25)<br />
Case "100%"<br />
scale = CSng(1.0)<br />
Case "75%"<br />
scale = CSng(0.75)<br />
Case "50%"<br />
scale = CSng(0.5)<br />
Case "25%"<br />
scale = CSng(0.25)<br />
Case "Fit Width"<br />
scale = CSng((panPreview.Width - 17) / bitmapSource.Width)<br />
Case Else<br />
Module1.setErrMsg("Error on Wrong Zoom Scale")<br />
Exit Sub<br />
End Select<br />
<br />
'If scale = CSng(9.9) Then<br />
' scale = CSng((picPreview.Width) / bitmapSource.Width)<br />
'End If<br />
bitmapDestination = New Bitmap(CInt(bitmapSource.Width * scale), CInt(bitmapSource.Height * scale))<br />
graphicDestination = Graphics.FromImage(bitmapDestination)<br />
graphicDestination.DrawImage(bitmapSource, 0, 0, bitmapDestination.Width + 1, bitmapDestination.Height + 1)<br />
picPreview.Width = bitmapDestination.Width<br />
picPreview.Height = bitmapDestination.Height<br />
picPreview.Image = bitmapDestination<br />
bitmapSource.Dispose()<br />
graphicDestination.Dispose()<br />
Else<br />
picPreview.Image = Nothing<br />
End If<br />
End Sub<br />
When I go thorugh this function to repeat the same picture Time by time,
The memory accumulate 3MB each time!! 
Anyone can help me to see what the problem is??
How can I improve it?
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And stop looking at TaskManager to see how much memory your using. You're actually seeing how much memory the CLR's virtual machine is holding onto, NOT much much memory your app is actually using. Use the Performance Monitor and the .NET CLR Memory counters if you want to see how much memory your app is using.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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I know what you mean actually,
but the number of memory shown on the task manager will shown to the end user.
Can I make the number shown on Task Manager is also low?
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cylix2000 wrote: but the number of memory shown on the task manager will shown to the end user.
So what?
cylix2000 wrote: Can I make the number shown on Task Manager is also low?
Not without calling the GarbageCollector directly. This is never done, unless you have a really good reason for doing it and know the consequences are! Doing this "just because I don't want my customer to think my app is a memory hog" is not good enough. The GC is self-tuning. You WILL cause your app major performance problems by constantly forcing the GC to run early.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Dave Kreskowiak wrote: cylix2000 wrote:
but the number of memory shown on the task manager will shown to the end user.
So what?
IMHO
It did happen alot, customers asking about our application perfomance, especially when we were selling the application. They will start saying something like "my old program or another program ( using another language ) didnt behave like this. are you sure your program is ok?". And then they start to "feel" that when running our application, they computer run slower. And also customers, most of them, didnt have IT background. Explaining them about what behind it, is sometime useless. What they see is what they believe.
The result of this are unsatisfied customer and a change of loosing business opportunities.
That's why a lot of people been asking and they will keep asking about it in the future. In CP forum itself, almost everyday there's a question about it.
CMIIW
WiL
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shiroamachi wrote: They will start saying something like "my old program or another program ( using another language ) didnt behave like this. are you sure your program is ok?". And then they start to "feel" that when running our application, they computer run slower.
This is a consequence of the environment and tools you are using - in this case Microsoft Windows, .NET Framework and VB. There are ways around it but they ALL include either rewriting the program in a different language or using different libraries or both. I know one guy who does all his own programming and never uses the framework nor the VC++ class libraries. As a consequence he has very compact and efficient code BUT it takes him MUCH MUCH longer to write, debug etc. That's the tradeoff by using rapid application development tools. (BTW, Microsoft is not the only supplier of resource-hungry dev tools.)
shiroamachi wrote: And also customers, most of them, didnt have IT background. Explaining them about what behind it, is sometime useless. What they see is what they believe.
I know what you mean. Non-IT trained (savvy) people never understand, but most of them never understand how an internal combustion engine works either since they are not trained mechanics but they still drive them to work everyday.
shiroamachi wrote: The result of this are unsatisfied customer and a change of loosing business opportunities.
That's why a lot of people been asking and they will keep asking about it in the future.
This is the job of the pre-sales guys and sales reps. They should properly manage the customer's expectations and be ready for the inevitable "why is it so" questions.
shiroamachi wrote: In CP forum itself, almost everyday there's a question about it.
Yes, sadly not many developers understand it either.
...Steve
"Give a man a fish and you've fed him for a day. Teach him how to fish and you've fed him for life." (Translation: I'll show you the way, but not write the code for you.) I read that somewhere once
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In VB.NET, when some huge data processing is going on, the form turns blank (Nothing is visible to the user, sort of hangs). However, the processing goes on correctly and the form becomes normal after the processing is completed. Can someone tell me how this can be prevented. Thnx...
With Best Regards,
Mayur
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mayhem_rules wrote: when some huge data processing is going on
Use a thread for processing this data.
You are doing processing in the main GUI thread. Hence it hangs.
Branch out the processing onto a different thread. You'll see the difference.
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--Owner Drawn
--Nothing special
--Defeat is temporary but surrender is permanent
--Never say quits
--Jesus is Lord
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