I have my VB.NET exam tomorrow and I have a list of potential questions, and there is this one question I really fail to find a good explanation for. it gives me this function:
Dim x, y as Single
y=2
y=x+10
MsgBox(x)
it returns 0... and I am supposed to explain what that happened. I have tried changing the numbers so it gives a positive number, and then it works properly... I have tried changing the type too, and still 0.
My problem is with the following API.
Private Declare Function GetKeyState Lib "user32" (ByVal keyCode As Integer) As Integer In Windows XP, I could simply use the API like this: If GetKeyState(Keys.Left) < 0 Then 'Move Left If the key was pressed, it was a certain number below 0, the number itself alternated each time you pressed the key but it was always below 0.
My problem is that in Windows 7, when you press the Left key, the number isn't the same, in fact the number isn't even negative anymore. This problem tricked me at first into thinking the API didn't even work as when I ran the .exe of course my code did nothing since GetKeyState never returned a number below 0. I tested the value itself though and found that it never goes negative, the number for the key just decreases a little.
The weird thing is, while the .exe from the Debug folder proved my point that the GetKeyState number was different and thus the program didn't work, running the .exe from the Release folder actually worked, the controls were fine and the API returned numbers less than 0 for GetKeyState. But the .exe from the release folder was built with my old XP computer, as soon as I made a new build with my windows 7 computer the API stopped working again.
Why did Windows 7 change the number returned for when the key is down, is there a way to change it back without having to include some large package with my program? Why did the build from my XP computer work at first? Also it was only the one from the release folder, not the debug one, even though they were both from the XP computer.
I tested some more on windows 7 and found that every time I run the program, the number returned by GetKeyState is completely different. When the key is down the number is 1,000,000 units higher than up, but other than that the number is random each program start.
I have a program that calculates values of a function, say f, with respect to another variable, say L.I have an array of f(L), for L going from 0 to a given integer value, say t-1 in steps of a value i.I need to export the values of this function to an Excel spreadsheet in a given column, and to do this, I would like to re-index the function f, since i is much less than one, and so the following loop I use (see below) won't work:
For L = 0 To t - 1 Step i
Sheet.Cells(L, 1) = L
Sheet.Cells(L + 1, 2) = f(L)
Next L
The first code in the loop will essentially load the values of L itself, at which the function is defined and calculated, and the next line will load the values of the function at each value of L.Since the indexes of the row and columns in an excel spreadsheet only go in steps of 1, I need to convert the indexes of the function, or the indexes to which L is loaded, so that it would be scaled so that the first entry corresponds to L=0, but the next is L=i, but loaded into row number 2, etc.
I get an error on the last line of sub where I am trying to assign a combobox to a column which is a textbox.error:Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index[code]....
View 3 RepliesI have a problem with the combox its only displaying the first item in the list its being populated by a webserice call the drop down in question is comboboxmodel now the manufacture one is fine and sets as it should any reason as to why the comboboxmodel would not. [code]
View 1 RepliesI recently installed Visual Studio 2008 Professional (Finally!) and I was going to use it for XNA programming. (I know XNA is C#) and my problem is that the templates for XNA aren't showing up in VS, how do I fix it?
View 5 RepliesI'm using a masked text box control. It has a property, ValidatingType, that is not available at designtime so it doesn't appear in the properties window of the IDE. The IDE has two drop-downs where you can select an object in your project on the left drop-down and see the associated members on the right drop-down.
My question is: Why, if I select my masked text box control on the left drop-down, don't I see the ValidatingType property on the right drop-down? All the events for the text box appear, why not the property members as well? Perhaps because it only shows properties that I code for an object?
I have an MDI application. Upon starting it, the MDI form is instantiated, then it kicks off a Username/Password log-in form and makes itself invisible(user never sees the MDI form). If the user logs in, the log-in form becomes invisible and the MDI form becomes visible. This works fine, except for one user.When the log-in form comes up, the MDI form is also visible. If he clicks on something, it crashes(certain variables aren't set at that point). If he logs in, however, the log-in goes invisble and everything works fine. This guy is a network admin/IS type and has several versions/hotfixes of the .Net Framework installed. Could that be the problem? Does anyone know what could be causing this problem for this one user and no one else?
View 2 RepliesI'm trying to search through all tabs to find a specific text. if the text is found, the tab will be hidden, or shown.
I tried this to hide:
btnHide
Dim txt As Object
Dim tabp As TabPage
For Each tabp In TabControl1.TabPages
[Code].....
I've read that more people have this issue, but it never seems solved. Anyone that knows how to solve this?
View 20 RepliesI set up SQL Server 2008 loaded VS2008 and all the ODBC drivers.All ODBC connections for DS and DGV's and using connection strings. I managed to get the connections working when I tested this on a new program.When I copy all the files from my other computer and try to view this it works with the connection string and connects to SQL server fine.But with the dgv I see nothing. Yet if I preview the datasets I get the result I am expecting
View 3 RepliesVS 2008 showing who is currently logged in statusstrip
View 2 RepliesI have a database and I was thinking about using either a List Box or Data Grid to show the data. Is there is another way of showing the data? Also, when the user 'double-clicks' on the data in the List Box or Data Grid then I would like the information to come up in a new form. I know how to show a new form but I don't know how to get the information from the one that has been clicked.
View 12 RepliesI was able to make my progress bar transparent, and I have a textbox, I want to see what's in the textbox behind the progress bar, but the progress bar it's not not showing it.
ProgressBar1.BackColor = Me.BackColor
me.backcolor = transparent
I have a form that has many checkboxes located on a tab control with 3 tabs each tab has checkboxes on it.I have a button that when pressed selects all the checkboxes. That does work and it does execute all that were selected. However there are no checkmarks appearing at all. This worked before! It seems like the more checkboxes I added to the form the less they properly showed f they were checked or unchecked. Now none of them show unless I close the form and reopen it then all of the boxes are checked like they should be when the select all button is pressed.
View 12 RepliesIm having a problem with my project i have changed the design of my form and when i run the program its still showing the old design how can i sort this?.
View 8 RepliesWhy would this code - that loads lots of VENDORS into this dataset - only show "1 of (1)" on the binding navigator?
VendorBS is the BINDING SOURCE.
Private Sub vendorLoad()
Dim connectString As String = "Server=fps-lap-szsqlexpress; Initial Catalog=Casefiles; Integrated Security=SSPI"
[Code]....
how can i get data from mysql table and show it in listbox in visual basic 2008
mysql table
id
filename varchar 255
filetime timestamp
and it is windows application
Searching for data in Access then showing output with VB 2008
View 6 RepliesI am working on implementing cell level error indication in my app and I have it set up to where it shows the error icon correctly and I tried using the datagridview FAQ sample code to show an errortooltip as well. I can watch as I set the errortooltip to have the proper data and display control (in mousemove event), yet the second I finish my mousemove event it fires the mouseleave event and resets my tooltip before the user ever has a chance to see it.
Here's my:
' show and hide the tooltip for error
Private Sub ChuteSinglesDataGridView_CellMouseMove(ByVal sender As Object, ByVal e As DataGridViewCellMouseEventArgs) Handles ChuteSinglesDataGridView.CellMouseMove
If cellInError.X = e.ColumnIndex AndAlso cellInError.Y = e.RowIndex Then
Dim cell As DataGridViewCell = ChuteSinglesDataGridView(e.ColumnIndex, e.RowIndex)
[Code] .....
This is my code at the moment. I want the TextBox to show the Directory of the file. (C:Documents and SettingsUserDesktopFile)
This is my TextBox Code
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
Me.Text = OpenFileDialog1.FileName
End Sub
This is my Button Code
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
OpenFileDialog1.ShowDialog()
End Sub
It is times like these that I miss the old VB6 language I wish I could hide the current forn and show another form which - this is the important thing - to be on the same level that the previous form was . You see , I used to use this code :
Me.Hide Form2.Show However , sometimes in VB .NET this does not work the way I want it to . You see , the current form does get hidden and Form2 is shown indeed ; however , Form2 is shown somewhere in the background . If there are other programs opened at that time , then Form2 is shown behind all those programs , that's what I mean by saying I want it to be shown in the same level as the previous form was the only way out , I found , was to reverse the code :
Form2.Show Me.Hide In this way Form2 is successfully shown right where the previous form was shown (above the other programs) but in some cases this also is not pleasant because it might take some time for Form2 to load while at the same time the previous form is still visible on the screen and therefore for a slight time both forms are shown one over the other , which is surely not nice . That's why I still want to first hide the first form and later show Form2 .
How would I go about forcing a file to download from the web browser control so that instead of a file dialog box showing it will automatically download to a set folder?
View 4 RepliesI am trying to write the following application. A project has initial investment, yearly revenue and yearly expenses. The program should be able to take these data and calculate the break-even year, i.e. when the cumulative profits become 0. Also, it should have a listbox that would list the cumulative profit for 10 years. Refer to the example below. Now I know how to show it in the listbox but I am having trouble showing the break-even year. I know how to calculate it but how do you show it in years.
View 8 RepliesIn C# we can declare a decimal number as negative zero i.e usingDecimal x = -0.0M we can define a variable x which holds value i.e negative zero. +ve zero can be differentiated from -ve zero using Decimal.GetBits method and looking at its MSB
View 4 RepliesI'm having an issue with my app where IE will get brought to the front of the screen when I am switching between forms. Basically I have a form with the man menu which consist of a few command buttons that will start up another form once a user clicks on the button. I do not want the users loading up multiple forms in my application, so once they load one form I end up hiding the main form. So my code looks as shown below when a button is clicked.
[Code]...
I am using VB Exopress 2008 and SQl Server Express 2008 in Windows Vista Home Premium. I have created a dataset after importing all tables and queries from MS Access to SQL Server. I have now added a view in SQL Server that I want to access and use in VB Express. However on clicking "Refresh" for the dataset the new view does not display in the available objects, only those I originally imported and opened with the original dataset. What, pleas am I doing wrong? How can I see this new View?
View 3 RepliesI am trying to show my excel chart in visual basic listbox and it does not work. I have added the reference of microsoft.office.interop.excel in my code i have put the range of column "A" and i do not know how to change the range to where the chart is in the excel.
Here is my code!
[Code]....
I have attached the excel file screen shot if that can help in any way...So basically When i click on the button in VB than it should show me the excel chart. My code just shows me the column "A" which shows me the "data" column only from the excel file.
I have created a custom Combobox and added it to my toolbox, and it works well. Now I have added a custom ListBox to the same file as the combo box, but it does not show on my designer when I place it. I can however add it at runtime.
''ComboBox
<DefaultEvent("SelectedIndexChanged"), _
ToolboxBitmap(GetType(System.Windows.Forms.ComboBox))> _
Public Class ProjectsComboBox
Inherits ComboBox
''My Customization
[Code] .....
I have tried removing the "DefaultEvent..." and still no dice.
I can't claim credit for this code but I think it's cool. It will show the entire contents of an item in a tooltip even when the columns are truncating it. Drop a tooltip and listview container on your form with the default name.
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
ListView1.Clear()
ListView1.View = View.Details
[Code] .....
