Clean Up App And Deal With The Async Calls?
Mar 16, 2010
My app is basically talking to a device via RS232. I need to 'listen' to the data received and do certain things based on it, update labels, etc. When I started, I only had a couple cross-thread calls and I used JMC's example to get by that. Now my app is bigger and I am calling the ThreadProcSafe all the time. I am hoping there is an easier way so I don't have to create sub routines for every control. Here's the relevant parts of my code.
Private Sub StepperSerialPort_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles StepperSerialPort.DataReceived
Dim ReceiveBuffer As String
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Feb 9, 2010
I've created a Delegate that I intend to call Async.
[Code]...
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Feb 3, 2009
I am trying to run this
vb
Public Sub SendPing(ByVal strHostname As String, ByVal objSelectedNode As TreeNode)
Try
Dim objPing As New Ping
[code]....
My problem is that in this code (and I know it's a lame way to do it) I'm checking to see if the node is Green after the Ping has been completed to determine if the ping was successful. I would prefer to return a boolean value to be True if the ping was successful.
When it executes the SendPing on the DragDrop function, it starts that thread and executes the If statement to determine if the node is green, but the ping isnt complete. Now I have to do this function on many nodes at once, so I dont want this to be a single thread. Is it possible to return a value from an async call and then execute a function after that value has been returned, or will this have to be a single thread?
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Jan 26, 2012
Using the code example on the Twitterizer website I am trying to post a tweet to twitter with this code:
Dim asyncResult As IAsyncResult = TwitterStatusAsync.Update(
tokens.Tokens,
Tweet.Text,
[Code]....
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Jun 3, 2010
I'm trying to write a 'developer friendly' wrapper for the Windows API EnumWindows - the problem is that the API uses a callback function that gets invoked on another thread, where as I want my wrapper function to simplify this and make it more useful by working like any other normal synchronous function and just returning a value.
Now if the API just called the callback once that would be fine, as I would just call the API and make the wrapper function wait until it got a signal from the callback function telling it to continue... but the API calls the callback function over 100 times (once for every window handle that exists). The biggest problem is that there is nothing that indicates that any particular call to this callback function is the last one, so my wrapper function has no idea when it is safe to continue and return the list of window handles to the caller.
The only solution I could think of is to do this:
1. The wrapper function calls the API and starts a timer that waits 2 seconds before it raises the Elapsed event. The wrapper function then pauses until it receives a signal (ManualResetEvent)
2. Each time the callback function is raised by the API on a different thread, it stops the timer (so this is before the 2 seconds have elapsed), adds the current window handle that was passed in by the API to the list of handles, then starts the timer again.
3. If the timer reaches its 2 second interval then it is assumed that we are at the end of the windows because otherwise the callback would have stopped the timer. So the timer's Elapsed event handler is what signals the original thread (that the wrapper function is executing on) to continue as we now have a complete list of windows to return.
This works fine and does exactly what I want... but I dont like it.
I dont like forcing the caller to wait an extra 2 seconds after the API has done its last callback but more importantly I dont like assuming that the API will never take longer than 2 seconds between callbacks. In reality on my PC it is never anywhere near that long between callbacks, it is something like 200 miliseconds, but I have no idea how long it would be on a slower PC and I want this to be completely reliable.
[URL]
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May 8, 2010
What the Win32 API is? I have looked around but no where really outlines what it is. Is it basically a set of procedures, outlined by Microsoft for programmers in order to get services from the operating system? In essence is it the equivalent to making system calls abd and library calls in UNIX? And yes I now Windows makes library calls too.
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Mar 4, 2010
I have been using DBTransaction for my current projects that access a single database. However, I read some documentation on TransactionScope and was wondering in which scenario would using TransactionScope be better? Or should I be replacing DbTransaction calls with calls to TransactionScope?
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Aug 17, 2011
I am using VB 2005 and MS Access 2007.Some of business name has apostrophe(') and I need to know how SQL deal with this name.For example
sqlStr = "SELECT * FROM AddressTable WHERE BusinessName=" & "'" & updateBName & "'"
in this case, if updateBName is "Den's Nail", the real SQL is
"SELECT * FROM AddressChangeTable WHERE BusinessName='Den's Nail'"
and this code generates Error Message.Is there any way to prevent error ?Or do I have to remove all apostrophe(') in Business Name?
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Aug 1, 2010
how to deal with attachment fields using VB.NET?
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Feb 28, 2010
I have following data in my table:
slno Name Age City
1 Ron 22 Dallas
2 Jonny 26 Texas
Now i use the following method to access data:
Try
Using connection As New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFilename=E:Visual Studio 2008ProjectsSmart SyncronixSmart SyncronixSmartDB.mdf;Integrated Security=True;User Instance=True")
[Code]....
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Jul 27, 2011
TabControl1. It is the only control that is created in design time. My text editor is a tabbed program. I have a addtab() function that whenever teh user clicks the toolstrip addtab, the tabcontrol adds tabs. THe code below is for the addtab()
Private Sub AddTab(Optional ByVal file As String = Nothing)
NewRTB.AllowDrop = True
NewTab.AllowDrop = True
[code].....
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Sep 1, 2010
how i can but the attributes that exist in web page in vb.net list and what are the differences between arraylist and list in vb.net???
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Jul 7, 2010
I've recently been given the task of finishing an incomplete project for my University. It'll count as credit for one Class so I'll shave a month off of my studies!
[Code]...
Methods returning numbers just for the hell of it, passwords being saved in plaintext, you name it.
I have a meeting with the original author and I don't know how to handle this situation because I'm quite green in this area. How can I tactfully mention that I want to rewrite the whole thing?
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Feb 1, 2011
I was trying to add two quantities at different rows of same description i.e same product_name and same item_pack.1st I want to check the table if it contains the same description or not by comparing with the first record and so on. When found, I'll add up the quantities and then to delete that particular row (to avoid duplicate search). But when I delete the row the particular row, next time it throws an out of index exception
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Jul 20, 2011
I've received a text file in which the text is like this, ãYAHOO.COM. When I'm debugging in Visual Studio, the value I see for the character is "�"c. Firstly can anyone tell what is the character before yahoo. Is it a special character or some html character, and what is the character that I'm seeing in VS while debugging.So it goes like this, the ascii value of the character turns out to be 63.But when I write the value to a file it generates 3 characters whose ascii values are above 127.
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Nov 4, 2010
I am creating a VB.Net program to deal out five random playing cards.For that purpose i checked the following tutorial - [URL]..It works great. But It has too much functionality I just want to get rid of the unwanted code to just dealing out 5 random cards. functions and classes from thius program that I should use.
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Feb 23, 2009
I've been trying to improve the efficiency of my giant program and I know that using a textbox to deal with a string is terribly inefficient.
Function CollectionSplit(ByVal TheString As String, ByVal TheSeperator As String)
Dim tb As New TextBox
tb.Text = TheString.Replace(TheSeperator, Environment.NewLine)
Dim returnable As New Collection
For Each x As String In tb.Lines
If Not x.Length = 0 Then returnable.Add(x)
Next
Return returnable
End Function
What it does is convert a string of "1,2,3" into a collection of the 3 separate items for use later on.
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Aug 28, 2009
[code]...
I got an Error about the INSERT INTO statement at command.executenonquery, but Im not seeing it. Could it be something else?
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Apr 27, 2012
I am trying to write a VB .NET program that runs a Perl script and reads and uses the standard output. I'd like to be able to handle each line separately as it is printed, and update my program display accordingly. Here's some code I have "written" (read: "mostly copied off the internet"):
Private WithEvents pscript As Process
Private Sub myProgram_Load(sender As Object, e As System.EventArgs) Handles Me.Load
pscript = New Process()
[Code]....
This works with one problem: the program waits until the test script has run to completion, and then fires several OutputDataReceived events one after the other. This means that when I make it use the real script, it's likely to do nothing for as much as several hours, and then have to deal with, like, 5,000 events at once, despite the fact that stuff was being printed at fairly regular intervals throughout that time.
Is there any way I can make it deal with each line of text when it is written, instead of all of it at once at the end?
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Mar 24, 2011
Suppose I have an interface IFoo with implementation classes VideoFoo, AudioFoo, and TextFoo. Suppose further that I cannot modify any of that code. Suppose that I would then like to write a function that acts differently based on the runtime type of IFoo, such as
[Code]...
Then I have to do my "If TypeOf ... Is" again. How can I refactor this to take advantage of the polymorphism of the implementations of IFoo without manually checking the types? (in VB.NET, though my question applies to C# too)
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Apr 6, 2010
How to deal with Adobe InDesign files in VB.Net 2008 such as searching for text or insert a picture?
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Nov 27, 2010
How is it possible to deal with incredibly long (large) numbers in vb.net?I am working on Problem 25 in Project Euler, and my program cannot handle these computations.Is there a data type that can handle thousands of digits?
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Mar 16, 2009
Sounds simple enough, but its not working. In this example, I want to set the values of 3 fields to equal a 4th. I could do something like this..[code]...
Values in the param array did not get updated in the return! I was expecting to have all of the final values now be "1", like they are in the Function.
Is there any way to get an update-able ParamArray collection like this? ParamArray must be declared ByVal, but with a reference type like String, shouldn't that only make a copy of the pointer and allow me to change the underlying value?
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Jul 5, 2009
My main goal is to have an excel spreadsheet that automatically plots the overall success of my stock portfolio over time (% change over time). I've been able to incorporate stock data into my spreadsheet by linking it to the web, but the trouble is the spreadsheet will keep no history of what the previous stock values were, so I can't graph how things change over time. This sounds like it might be too complicated to be built in to excel, so I was wondering if anyone knew how to program this in Visual Basic. Maybe something like this.... If refresh then new cell plus new time stamp. Another possibility would be to have a whole bunch of cells that refresh only once but at longer and longer intervals, e.g.,
Day Stock value
1 refresh at Day 1
2 refresh at Day 2
3 refresh at Day 3
etc..
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Jun 2, 2009
I am making a program to deal with sine/cosine functions
If rdbsideA.Checked = True Then
Do While AngleB > 0
SideA = (SideB * Math.Sin(txtAngleA.Text)) / Math.Sin(AngleB)
Loop
MsgBox("The Length of Side A is ", SideA)
End If
That is if the user seleects to find side a. When the messagebox pops up, it doesnt state the previous calculation, why is that?
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Nov 10, 2011
I have handed this assignment in and it works albeit not in the most elegant way. I am taking my second programming class ever and I would love for some feedback and answers to a few questions i have. First, what would be a better way to display the correct image to the corresponding card. Using all those if statements seems ridiculous, but i cant see a way around having card 1 possibly equal each value from every suit, card 2 equal each value from every suit, etc.
Second, my professor wants us to be able to record the seed value so that we could then plug it back in and return the hand that was shown when it was created. i have done this but I am a bit confused. The seed shows up as a value from 0-999, but when you use the combination formula to figure the total possible amount of hands you get over 2.5 million. Since i only have 1000 seed values does that mean that multiple hands might share the same seed value or does that number (0-999) mean something different eache time? Sorry if my explaination seems confusing.
Third, I am always looking for advice on better ways to do things. If anyone has free time and would like to offer constructive critisism I would be grateful.Below is the code. I only left in picturebox display for 1 suit so as to shorten the total amount shown. I also removed code for other buttons and stuff.
Public Class Form1
Private Sub btnShuffle_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnShuffle.Click
' Variable Declarations
Dim intSuit As Integer ' Row
Dim intCardValue As Integer ' Column
[Code]...
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Mar 11, 2009
so I've come across something which is perhaps a flaw in the Extension method .CopyToDataTable. This method is used by Importing (in VB.NET) System.Data.DataTableExtensions and then calling the method against an IEnumerable. You would do this if you want to filter a Datatable using LINQ, and then restore the DataTable at the end.
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Dec 5, 2010
Create a class to deal with records from the Classes table, much like the Student class we created in Lecture #17 handles Students records. The name of the class should be Ualb_Class (note we cannot use Class, as it is a reserved word in VBA). All of the fields should have corresponding properties. There are few considerations:
The class (course) code, department code, and course number are set at Initialize, so there is only a Get property method for those
The property for Meeting Day only accepts one of the values defined in the table. You can decide whether to accept an integer value or a string value of the days represented.
You are also to code the Initialize method, much like we coded the Initialize method for the Student class in Lecture #17. In the Initialize method, you will use the InputBox function to obtain the department code and course number. use a different InputBox for each value, so you don't have to mess with separating the single text value returned from that function. The Course Code will be obtained by using a function that has already been created, called GetNewCourseID. It has no parameters.
TABLE: Classes
Field Name
Data type
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Jan 10, 2012
I want to retrieve total value from sales table in sqlcommand object. Below is my sample code.I will get error if there was no data in the tabel that matched my query saying that null could not be converted into decimal.
I would not get error if there was data that matched my query and returned the total value in tmpSales variable.My question is what is the best way to deal with this situation?
Dim CmdTmp As System.Data.SqlClient.SqlCommand
Dim tmpSales As Decimal
CmdSales = New System.Data.SqlClient.SqlCommand("SELECT SUM(Total) FROM Sales WHERE Date>= '1 Jan 2011' And Date<= '30 Jan 2011", ConDB)tmpSales = CmdSales.ExecuteScalar
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Jun 15, 2010
[code] If there is an error inside the Using block how do you clean up the sr object? The sr object is not in scope in ErrHandler so sr.Close() cannot be called. Does the Using block cleanup any resources automatically even if there is an error?
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