VS 2008 Declare Variables Inside Each Event Handler / Program Runs
Mar 29, 2010
I am teaching myself VB, and when I try to run this program, I am getting "An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object." If I was to declare the variables inside each event handler, the program runs, but why won't it run when I make the scope public? Seems repititous having to declare the variables in every event handler. [code]
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Nov 11, 2011
Everyting is OK, but when I click on F5, it refresh the page and run the code another time. This means a new record is added to the data base on each F5.This is my code, do you have any advices?
Imports System.Data.OleDb
Partial Class Default2
Inherits System.Web.UI.Page
[code]....
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Nov 9, 2009
I am creating a very simple game for a project. There is opportunity for bonus marks, and one thing I would like to do is be able to "save" the game. The only thing I need to do is save about 4 variables to be recalled the next time the program runs.
What is the best way to do this?
I have searched Google, and there are ways to link the program to an Access database, but that seams a little extreme. I tried seeing if you can make an XML file to hold them, but I can't really find any good information.
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Apr 18, 2011
The event handlers in my parent class are never called though the events are raised in the child class.
The Code:
Public Class childForm
Public Event checkboxchangedEvent(ByVal checkbox1 As Boolean, ByVal checkbox2 As Boolean)
Private Sub checkboxchanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged, CheckBox2.CheckedChanged
[code]....
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Jul 27, 2011
I have a VB 2008 console application .NET 3.5 who handles large data tables in a SQL 2005/8 database. Sometimes when SQL server do not response as application expect. Then SQL Connection change status from open. I try to get the event of changed connection string before error occurs.
1 - SQL Connection status changes from open to another status
2 - When this event fires a fix sub routine or function starts and fix the sql connection
3 - Return back where SQL Connection was when status was affected by program.
My app is a large list of SQL Commands who runs in a class orginsed as a simple list of sqlcommands.When a SQL Connection fails I will start at the last point in the program after SQL Connection are open again.
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Jan 12, 2012
This code is part of AjaxControlToolkitSampleSite. To be exact, it is in the AsyncFileUpload control[code]...
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Aug 27, 2011
How do I get a Event Handler to fire from within a nother Event Handler?
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Jul 8, 2010
I am creating aplication that displays images in many different ways using Picture Boxes. Single page with tabs, double page using fading in/out effect, double page 'page flip' effect and single page auto scroll effect which I have problem with. I am dinamicaly creating picture boxes, loading images, placing 'path' to a file in tag and adding handler to each picture box. All fine...
[Code]...
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Jan 10, 2008
In an attempt to learn how to program in VB I thought I would have a go at working through some of the examples in the VB2008 express edition documentation. The following example expects an event handler to exist. I am having difficulty understanding how to declare an event handler.I have lifted the following from the VB2008 express edition documentation.[URL] CONTROLS AT RUN TIME... The Visual Basic 2008 example also assumes that an event handler named TextChangedHandler exists for the first TextBox control. - I NEED TO DO THIS. Private Sub TextBoxes_AddText(ByVal sender As System.Object, ByVal e As System.EventArgs)' Declare a new TextBox.Dim TextBoxB As New TextBox' Set the location below the first TextBoxTextBoxB.Left = TextBoxA.LeftTextBoxB.Top = TextBoxA.Top + 10' Add the TextBox to the form's Controls collection.Me.Controls.Add(TextBoxB)AddHandler TextBoxB.TextChanged, AddressOf TextChangedHandlerEnd SubSo I did something like this ...Private Sub TextChangedHandler(ByVal sender As System.Object, ByVal e As System.EventArgs) _Handles TextBoxA.TextChanged End
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Jul 3, 2009
[code]What is the syntax for using variables inside of quotes?
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May 8, 2011
Can someone help me with the code for an Event Handler for colorAnimation in VB.net. All I get so far is code in c#, which I do not follow very well. Please also show how to call or raise it from a control e.g. a button.
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Jul 16, 2011
How can i add one more parameter in System Events for ex : I want to add a parameter in Button Click Event.
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Oct 30, 2009
I've recently learned a new trick. I never realized you could write a sub and then handle multiple controls' events right in the sub.instead of handling each controls click event, for example.
[Code]...
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Mar 25, 2010
if you have this in your Application events: Private Sub MyApplication_UnhandledException(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.ApplicationServices.UnhandledExceptionEventArgs) _ Handles Me.UnhandledException 'test to make ceratin handlers both fire Debug.WriteLine("AppEventFired") End Sub nd to test it you do this
Throw New Exception("1") shouldn't the Debug.WriteLine("AppEventFired") line execute? It isn't that I can tell and I have checked that I am running in Debug, not Release.
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Oct 28, 2009
Perhaps surprisingly I haven't added an event handler programatically before and I'm having trouble getting my head around AddHandler.I am creating a series of DataGridView controls in a loop and want to subscribe to the CellFormatting event on each of them.The event handler signature is as follows;Private Sub ConfigureRows(ByVal sender As System.Object, yVal e As System.Windows.Forms.DataGridViewCellFormattingEventArgs)This works fine when I enter it in the visual editor properties box but I can't figure out how to give it the correct arguments using AddHandler.
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Dec 31, 2009
I have this code
If e.KeyCode = Keys.D0 Or e.KeyCode = Keys.D1 Or e.KeyCode = Keys.D2 Or e.KeyCode = Keys.D3 Or e.KeyCode = Keys.D4 Or e.KeyCode = Keys.D5 Or e.KeyCode = Keys.D6 Or e.KeyCode = Keys.D7 Or e.KeyCode = Keys.D8 Or e.KeyCode = Keys.D9 Or e.KeyCode = Keys.Oemplus Then
[Code]....
The output WILL be 189 when I press the - sign. But when I check "Keys.OemMinus" it stands for 189 and when I replace "Keys.OemMinus" with 189 it won't work either!
I checked the Resources file and it's correct. The picture just doesnt change, only shows the last pressed button...
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Sep 30, 2009
Simply stated, I want to call the Panel1_Paint event handler from the Button1_Click event. Is this possible? If so, How? IE: Click the button and it paints the panel.
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Dec 6, 2009
I have a simple, but important question: How can I raise events of my form1 on another module/form?My form tempalte is crowded with events (50 of them contextmenustrip events)How can I place those events on another form/module to clean it up a little?
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Jul 4, 2009
With reference to my previous thread on Paint event handler.. [URL] I went to read up more on Paint Event Handler.. I have a button which draw out a path based on the user selection.. Below contains the drawing of the path portion of the button click event code
[Code]...
However It did not activate the paint event when I clicked on the button.. Instead, the paint event still activate even before I click on the button? So can anyone teach me on how to activate the paint event when I click on a button?
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Aug 9, 2009
I wrote a simple auto login script to update my IP address on a certain website. Something really strange is happening now though. The first time I run the program, nothing happens. However, the second time I run the program, that instance will work fine. Then I look in task manager, and the first program is still running, using a whopping 50% of my CPU. I believe VB may be blocking off memory or something, as when two instances are running each is using around 25% of CPU. Then after the second one successfully completes, the first starts to use 50% again.
Here's my code below:
Option Strict Off
Public Class frmTest
Private Sub frmTest_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[Code] .....
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Mar 21, 2012
remove an event handler from within the event handler?
I have a class that gets data from a hand scanner. When the scan is complete and the data is validated, the class fires a custom "ScanComplete" event and returns the data in a custom EventArgs.
In the calling program, I'm creating an instance of the scanning class and adding a handler for the "ScanComplete" event. In the event handler I get the data that was scanned and then remove the handler.
It seems to be working but it feels wrong to remove the handler while I'm running inside the handler. Will this cause a problem?
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Apr 6, 2010
I am putting together a simple multiple column listbox. I call it Gridbox.The intent is to make a lightweight grid control mainly for displaying lists with columns. Minimal cell access i supported.
I wrote it with an IntegralWidth as well as an IntegralHeight.Of course I cannot support the Integral Width if there isn't at least one column in the Columns collection when the control is initialized.
To this end I call a Column Add() method in the UserControl New() Event.
So that one Column will be present when the control is placed on a form.
For some reason the New() UserControl Event is firing twice. So I end up with two columns not one.
I was under the impression that New() only fired once when the control was intialized. Where would
I put the code that creates the desired column if not there?
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Jun 3, 2011
And here I am with a new problem in my program When I debug it everything works fine (the buttons, progressbars, pinger, spambot, When I compile it and run the Executable file, it works too.When I run the Executable file on another computer (tried on 4 different ones) the program stops working and
I get this error:
{$ exception. "Failed to create the form For more information, see Exception.InnerException error: File or assembly ." Microsoft.VisualBasic.PowerPacks, Version = 9.0.0.0, Culture = neutral, PublicKeyToken = b03f5f7f11d50a3a "or one of its dependencies not found. The system can not find the file specified .."} System.Exception {System.InvalidOperationException}
[Code]...
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Feb 6, 2012
trying to figure out how to declare items here. here is the
[Code]...
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Mar 23, 2010
I've almost completed my first VB.Net app which is a rewrite of an old vba app I wrote.The last part that I need to write is the timed events part. What I have in VBA is quite straightforward.Every 500ms the Timer event runs through, it checks if certain variables have been flagged and if so runs the relevent code? Code is nothing major, just updates a networked device.I've looked into timers in .net but it seems like there are various routes that I can go down.
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Nov 27, 2010
I'm trying to complete this airline reservation application, but having a problem in this part of the question:Creat an event handler for the FlightBindingSource's PositionChanged event: select FlightBindingSource in the class Name combobox then select position changed in method name combobox to creat the FlightBindingSource's PositionChanged event handler. Write a code to access the currently displayed flight object and pass its flightNumber to method DisplayPassengers as a decimal.This Is my code so far:
HTML
Public Class AirlineReservationForm
Private database As New ReservationsDataClassesDataContext()
Private Sub FillAll()[code].....
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Dec 10, 2009
Is it at all possible to declare variables dynamically? Something like Dim Answers & i As ArrayList. What I'm trying to achieve is putting one or more answers to a question into an array. Or should I really be looking at a mult-dimensional array to store the question number and answer? How would I add to and access a multi-dimentional array? Anyway, here's the section of code:[code].......
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Aug 20, 2009
I'm new to VB.NET programming.What I'm confused about is the different ways one can declare a variable.Would someone please explain the difference between the two declarations below? [code]
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Aug 16, 2010
How I can declare global variables in vb.net that I can access them in all windows of my application?
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Jun 8, 2011
I am needing help in understanding how to declare variables properly. I am needing to write as program that calculates the commission for a sales person. I keep getting a error listed below. I thought I declared the salestextbox, costtextbox as integers correctly to use them in the calculation. I Copied my code below also. I have reread the chapter again and I am still lose.[code]
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