I have converted the following C# code to VB.NET.But I am unable to find the equivalent of C# "Unchecked" keyword in VB.NET.Below is the C# Code and following the C# Code is converted VB Code.After conversion and building the VB Code I am getting the error :"Constant expression not representable in type 'UInteger'." [code]
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So I'm trying to figure out how to correctly override GetHashCode() in VB for a large number of custom objects. A bit of searching leads me to this wonderful answer.Except there's one problem: VB lacks both the checked and unchecked keyword in .NET 4.0. As far as I can tell, anyways. So using Jon Skeet's implementation, I tried creating such an override on a rather simple class that has three main members: Name As String, Value As Int32, and [Type] As System.Type. Thus I come up with:
Public Overrides Function GetHashCode() As Int32
Dim hash As Int32 = 17
[code]....
Problem: Int32 is too small for even a simple object such as this. The particular instance I tested has "Name" as a simple 5-character string, and that hash alone was close enough to Int32's upper limit, that when it tried to calc the second field of the hash (Value), it overflowed. Because I can't find a VB equivalent for granular checked/unchecked support, I can't work around this.
I also do not want to remove Integer overflow checks across the entire project. This thing is maybe....40% complete (I made that up, TBH), and I have a lot more code to write, so I need these overflow checks in place for quite some time.
What would be the "safe" version of Jon's GetHashCode version for VB and Int32? Or, does .NET 4.0 have checked/unchecked in it somewhere that I'm not finding very easily on MSDN?
EDIT:Per the linked SO question, one of the unloved answers at the very bottom provided a quasi-solution. I say quasi because it feels like it's....cheating. Beggars can't be choosers, though, right?
Translated from from C# into a more readable VB and aligned to the object described above (Name, Value, Type), we get:
Public Overrides Function GetHashCode() As Int32
Return New With { _
Key .A = _Name, _
[code]....
This triggers the compiler apparently to "cheat" by generating an anonymous type, which it then compiles outside of the project namespace, presumably with integer overflow checks disabled, and allows the math to take place and simply wrap around when it overflows. It also seems to involve box opcodes, which I know to be performance hits. No unboxing, though.
But this raises an interesting question. Countless times, I've seen it stated here and elsewhere that both VB and C# generate the same IL code. This is clearly not the case 100% of the time...Like the use of C#'s unchecked keyword simply causes a different opcode to get emitted. So why do I continue to see the assumption that both produce the exact same IL keep getting repeated? </rhetorical-question>
Anyways, I'd rather find a solution that can be implemented within each object module. Having to create Anonymous Types for every single one of my objects is going to look messy from an ILDASM perspective. I'm not kidding when I say I have a lot of classes implemented in my project.My final implementation, which fits the constraints of GetHashCode, while still being fast and unique enough for VB is below, derived from the "Rotating Hash" example on this page:
'// The only sane way to do hashing in VB.NET because it lacks the
'// checked/unchecked keywords that C# has.
Public Const HASH_PRIME1 As Int32 = 4
[code]....
I also think the "Shift-Add-XOR" hash may also apply, but I haven't tested it.
We have a keyword 'app.path' in VB6 What is the equivalent key word in VB.NET
View 1 RepliesIn C# you can do this to make your member variable immutable: public readonly int y = 5; What is the equivalent "readonly" keyword in VB.NET?
View 1 RepliesIs there a LINQ To SQL equivalent to the SQL between keyword?[code]...
View 2 RepliesIs there a Java equivalent - specifically on Android - for VB.NET's Static keyword? For those not familiar with VB.NET, take the following code snippet...
Sub MyFunc()
Static myvar As Integer = 0
myvar += 1
[code].....
Is there a VB.NET equivalent to the C# var keyword? I would like to use it to retrieve the result of a LINQ query.
View 4 RepliesWhat is the vb.net expression of this c# expression ?
Frame.GetController<ShowNavigationItemController>().CustomShowNavigationItem += new EventHandler<CustomShowNavigationItemEventArgs>(WindowController1_CustomShowNavigationItem);
i didn't want to trust this one to any number of online conversion websites that I often use.I don't need to convert the declarations, just the expression '(byte)((flen & 0xff00) >> 8)'in
byte[] sendFrameData = new byte[280
ushort flen
sendFrameData[7] = (byte)((flen & 0xff00) >> 8);
I would like to know the equivalent expresion in VB for this C# expression: Container.TotalRowCount > 0 ? Math.Ceiling(((double)(Container.StartRowIndex + Container.MaximumRows) / Container.MaximumRows)) : 0
View 3 RepliesWe all know that this method will convert an expression text (string) to precompiled VisualBasicValue. Refer to this documentation for more details
VisualBasicDesignerHelper.CreatePrecompiledVisualBasicValue
I need to check if a given object implements an interface. In C# I would simply say:
if (x is IFoo) { }
Is using a TryCast() and then checking for Nothing the best way?
I have a project where I want to have checked arithmetic by default, except for one performance sensitive spot. Unfortunately, VB.Net doesn't have an 'unchecked' block.Ideally the framework would have some sort of integer type with explicitly unchecked arithmetic, but I didn't find anything like that. I did find that expression trees have binary expressions for unchecked operations, but the delegate overhead cancels out the unchecked advantage (and then some).
Currently I'm converting the inputs to UInt64/Int64 before doing the arithmetic, then converting back (with a bitwise And to ensure in-range). It's about 50% slower than unchecked arithmetic (according to profiling).
Moving the arithmetic-sensitive part to a project with unchecked arithmetic might work, but it seems like overkill to give it an assembly all to itself.
I have a Four radio button on the form. I want to make them in two groups.Now when i checked anyone the remaining three are unchecked. I want to make two radio buttons in one group and in another group two.Suppose in one group when i check one the other two in second group not unchecked. How i do it?
View 1 RepliesHow do I get all the radiobuttons to be unchecked when program is run? Right now there is always one button that is checked. Using VB2008. [URL]
View 9 RepliesI have an issue. When I check SelectAllCheckBox all checkbox column in ListView is checked. But when I unchecked one of row checkbox the SelectAllCheckBox is still checked. How to uncheck SelectAllCheckBox if one of row is unchecked? And second question is how highlight ListView rows when SlectAllCheckBox is checked?
[Code]...
I have this code:
Code:
Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
If CheckState.Checked Then
AmxModXInstallDir.Enabled = False
Button1.Enabled = False
[code]....
When i check the box, it enables all controls, if i uncheck it, nothing happens.
I want to create a solid checkbox that is checked by default, and is not clickable. If you click it, nothing will happen . how to do this?
View 2 Repliesfrom the code below I am trying to find out if checkBox1 is Checked or Unchecked. and then I want my settings to remember if it is checked or unchecked. so when the form is loaded I want my settings to load the last action.... ie checked or unchecked.
so if a user check's the checkbox1 then the message will not show, But if it is unchecked the the messageBox will be shown
Private Sub CheckBox1_CheckedChanged(sender As System.Object, e As System.EventArgs) Handles CheckBox1.CheckedChanged
If CheckBox1.Checked = True Then
[Code]....
I am using VB Stuido 2008, Net Framework 3.5.I have one Checkbox to Identify the record as Inactive if checked. When I load the form the checkbox is alway unchecked, which is what i want. However, when I go to add a new record the checkbox, not the text for the checkbox is always shaded green, not a checkmark. The checkbox then reacts as if it is checked. This makes it necessary to uncheck the checkbox or else all my record react as if checked.
in the table defintions I have set the default binding value to ((o)) which = unchecked. Iafter setting the default value to ((0)) I deleted the checkbox from my form and then replaced. Not I still get the checkbox shaded which reacts as if Checked.
I have a very stubborn check box . Let me tell you its story :There is Form1 with a button leading to Form2 . On Form2 there is located that stubborn check box I was telling you about . That check box has code in its CheckedChange event and accordingly to its Checked condition , it enables or disables some text boxes .Well , the first time Form2 is shown , that check box works fine : when I check it it enambles the text boxes and when I uncheck it , it disables those text boxes .Then , I press the button to return to Form1 . If needed , the code in the button is :Form1.ShowMe.CloseMy adventure starts when I show again Form2 ... This time the check box is acting weirdly . No matter if I check it or I uncheck it , it always disables the text boxes , as if it is constantly unchecked ! I can see it changing its checked state whenever I click on it , but it always runs the code to disable the text boxes.
I even used some break points in the code and found out that indeed it is the code that disables the text boxes that is called every time , no matter if the check box is checked or unchecked .I don't thing this has anything to do with the fact that this event is called by all the 4 check boxes on the form . After all , it is always the 1st check box that causes the problem (I can see it when moving the cursor over the genericindex variable) .
I am trying to decode yEnc data using the component found here:[URL]...It all converts fine, except for Line 173 of Decoder.cs which contains the c# keyword "unchecked".Without using unchecked I get an OverflowException.What is the correct way to implement this in VB?
[Code]...
I got this Error. below is my code.
GenerateTheList is function.Need help
Private Sub buttGenerate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttGenerate.Click
Dim thread1 As New Thread(New ThreadStart(GenerateTheList))
thread1.Start()
End Sub
While looking in the dataset designer for a database table I am doing in visual basic 2008 I found a line for expressions under the property menu for a specific column. I need to know the code that I would put in this expression line so that this column adds up the numbers I input into three other columns and displays that number in the column. I need it to automatically calculate this for each row in the database table.
View 13 RepliesPossible Duplicate: I have 4 checkboxes and 1 textbox in webform if i type in textbox 1,2 then checkbox1 & 2 will be checked ! I have 4 checkboxes and 1 textbox on a web-form. If I type 1,2 in the textbox, then checkbox1 and checkbox2 will be checked. The code for this is as below. But what I want is that when I type 1,2 then checkbox1 and checkbox2 should be disabled and unchecked.
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim separator As Char = ","c
Dim allIIDs As New List(Of Int32)
[code]....
I am using the following code for a checkbox, if checked it should print the text defined, unchceked, it clears the items in the ricktextbox. My problem is it prints fine (lets say it prints two lines) as defined, when I uncheck, it clears the text in rich text box, but when I check again, the text appears in the richtext box, but displayed from 4th line. I need to restart from the beginning/ or at least from the next available line. I cant use clear() since it erase all the contents as i have another 3 checkbox items placed.
If CheckBox1.Checked Then
richtextbox.SelectionColor() = Color.Blue
richtextbox.AppendText("Urgent:")
richtextbox.AppendText(CheckBox1.Text.ToString + vbNewLine)
Else
richtextbox.Refresh()
End If
The check box list has an event called "ItemChecked" or something, which triggers when an item is about to change its checked status.
So, it is before the check occurs.I couldn't find an event that occurs after the item has changed.. I want to execute some code only when an item is checked or unchecked.
Im creating a menustrip which can choose to draw the shape you want, and the colour you want to fill in the shape.For the colour part, I manage to choose multiple colour options. Example : If i checked red and blue colour, the shape of the colour would be purple. But when I want to uncheck the red color or blue color, it does not work.
Public Class Form2
Private Sub ExitToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExitToolStripMenuItem.Click
Me.Close()
End Sub
[code].....
I have a datagridview with 3 checkboxes, Yes, No and InV.At runtime, I want the user when he checks one checkbox the other two are unchecked by default. Therefore, at whatever one time ONLY one checkbox will be checked.
[Code]...
I'm trying to set my software up so that when I check the checkbox for winRAR to be installed, it'll pop up a new window asking if I want to install the 32 bit version or the 64 bit version. I have no problem getting the window to show up but than if I try to exit out of the window and than uncheck the box (in case it was accidentally checked) it'll just open the window again. I am thinking I have to tell vb that when I uncheck the box it shouldn't do anything.
Here's my code.
(I know that the Nothing under the Me.chk_rar.Checked = False doesn't work but I left that blank once and it just opened a bunch of windows and crashed my system. I know it says "E:Music" right now but I just pointed it there so that there was something there normally it'll point to the other window. If I need to created a new Form for every little window that I have for instance the little window that I want to pop up, do I need to create a new form just for that little window to ask which architecture is needed and than giving the options for 32 bit or 64 bit.
Private Sub chk_rar_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chk_rar.CheckedChanged
Me.chk_rar.Checked = True
Process.Start("E:Music")
Me.chk_rar.Checked = False
Nothing
End Sub
