Why Expressions Doesn't Support IdentityEquality
Sep 22, 2009There is no IdentityEqual item in ExpressionType enumeration. How can I construct expreesion tree with VB.NET Is operator?
View 1 RepliesThere is no IdentityEqual item in ExpressionType enumeration. How can I construct expreesion tree with VB.NET Is operator?
View 1 RepliesSince vb doesnt support pointers but c# does. I am using a wrapper dll that requires a pointer to some singles to be passed within the method. I get an error that the method has some parameter types that are not supported. How can i pass a pointer to this method if vb .net doesnt support pointers.
View 4 RepliesI have a query to retrieve DateDiff in my SQL:
SELECT Convert(char,DATEDIFF(m, Temp.Opening_Date, '2011-05-01')) As MonthDifference From Temp
It was successfully retrieve the data from SQL Server. But when I bind it to my vb.net datatable, the value is null. It's seems like vb.net datatable doesn't support datatype from DateDiff... What can I do?
Note: this is not a duplicate of Jeff's question. That question asked "Is an equivalent?" I know there isn't, and I want to know why! The reason I ask is that I've only just become clear on how important it is, and the conclusion seems very strange to me. The Exception Handling block of Microsoft's Enterprise Library advises us to use this pattern:
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The policy is defined in an XML file, so that means that if a customer has an issue, we can modify the policy to assist with tracking down (or perhaps papering over) the problem to give them a fast resolution until we deal with it properly - which may involve arguing with 3rd parties, about whose fault it all is. This is basically an acknowledgement of the simple fact that in real applications the number of exception types and their "recoverability" status is practically impossible to manage without a facility like this.
Meanwhile, the CLR team at MS says this is not an option, and it turns out those guys know what they're talking about! The problem is that right before the catch block runs, any finally blocks nested inside the try block will be executed. So those finally blocks may do any of the following: Harmlessly modify the program state (phew, lucky). Trash something important in the customer's data, because the program state is screwed up to an unknown degree. Disguise or destroy important evidence that we need to diagnose an issue - especially if we're talking about calls into native code. Throw another exception, adding to the general confusion and misery.
Note that the using statement and C++/CLI destructors are built on try/finally, so they're affected too. So clearly the catch/throw pattern for filtering exceptions is no good. What is actually needed is a way to filter exceptions, via a policy, without actually catching them and so triggering the execution of finally blocks, unless we find a policy that tells us the exception is safe to recover from. The CLR team blogged about this recently:
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Are shared properties accessible from a COM exposed .NET assembly?
Dim appExcel As Object
Dim objAppSingleton As Object
Set objAppSingleton = CreateObject("Pitchbook.CommonUtils.Application.PitchbookAppSingleton")[code].....
The line appExcel = objAppSingleton.CurrentPitchbookExcelApp gives the error:Run-time error '438': Object doesn't support this property or method
Why doesn't vb.net in Visual Studio 2010 have any Refactor support
View 14 RepliesI am writing a VB.NET app that has a piece which needs to send a small command to comm port 2 and get the return result. The problem is .NET doesnt have any support for serial communication seems like.
I just need to send the command "headtype" and get the result.
I have been again blessed with legacy code made (presumably) with vs 2008. It's a Visual Basic project with a dependency to SQLite. The actual problem is that it is needed to install and run on Windows 7. Now, I have VB 2008 express in which I opened the project and tried to run it. It threw an exception which was most likely due to the fact that SQLite.dll doesn't support Windows 7 (and/or 64 bit environments). The exception was System. BadImageFormatException. (ddl version was 1.0.65.0)
I read somewhere in the internet that in order to run it in Windows 7 you need to have newer version of it. I downloaded it and managed to change the reference to newer one. Now in the SQLite site it says it requires .net version 3.5 or 4.0. I know that I can change the target framework to 3.5 or even 4.0 but do I need to change some of the old references in the project properties? All the references seem to be to 2.0 libraries. Like System 2.0.0.0 and path to X:windowsMicrosoft. NETFrameworkv2.0.50727System.dll. Does this actually mean that the application is using .net 2.0 although it target framework would be 3.5 or 4.0?
And most importantly do I need to convert my application manually or by using some tool to .net 3.5 or 4.0 in order to get it running with new SQLite dll which requires 3.5 or 4.0?
I want to be able to add a range and get updated for the entire bulk. I also want to be able to cancel the action before it's done (i.e. collection changing besides the 'changed').
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I compiled some VB6 code on my Win7 x64 machine and the result .exe will not run correctly on any other machine. VB6 code is just a new template .exe file with one button, a reference to "Microsoft ActiveX Data Objects 2.6 Library" and the following code in the button press event: Dim db Set db = New ADODB.Connection It runs correctly on my machine, but no others (even other Win7 x64 machines) (Update: I found TWO other users where it runs and one of them is Jeff Atwood!, but most machines have the same problem)
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I am trying to change the background color of a tooltip
I am using tooltip.backgroundcolor = color.colr
No errors but thecolor doesn't change
I use Visual Studio 2003, VB.net, NetFramework 1.4 and Windows XP I have been using the following Code Snippet for a number of years in both Web Services and Windows Applications. However suddenly around the 29th September 2010 it has stopped sending E-Mails from both Web Services and Windows Applications. The same problem has happened not only to my own Network but on two other Networks, one using XP as its Server and the other using Server 2003. All 3 of these are using different ISPs.
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I see lambda expressions have become a very useful tool at some points in the language. I've been using them a lot and most of the time they fit really nice and make the code shorter and perhaps clearer.
Now.. I've seen some , I would say excessive use of them. Some people like them so much that try to use them everywhere they can.. Some times the C# code looks like a functional language. Other factors against are the cost using reflection by lambda and that not friendly to debugging.I would like to hear opinions about how good and how code clear it is to use more or less the lambda expressions. (this is not the better example, but let's say it was the trigger)I was writing the following code. The use of the delegate { return null; } helps me avoid having to ask if the event is null or not every time I have to use it.
public delegate ContactCellInfo.Guest AddGuest();
public event AddGuest GuestRequest = delegate { return null;}
Im using resharper and the wise resharper( even it some times literaly eats the memory) made me the following suggestion
public delegate ContactCellInfo.Guest AddGuest();
public event AddGuest GuestRequest = () => null;
At my point of view the code using the delegate looks clearer. I am not against the Lamdba expression just would like to hear some advices on how and when to use them.
if i do not need to evaluate all the expressions, am i right to say that there are benefits and no disadvantages of using AndAlso compared to using And
example:
if a=b And f=g And y=k
can be better done with:
if a=b AndAlso f=g AndAlso y=k
Functionally, is there any difference (apart from syntax onbviously) between lambda expressions in C# and VB.Net?EDIT: following up on CraigTP's answer: any references to the situation in .Net 4?EDIT: I'm asking because I'm used to C#, but for a next project the customer asks VB.Net. We're not a priori against that. We realize that most language constructs are supported in both languages. However, we're particularly fond of the way C# implements lambda expressions. We would like to have an overview of the differences with VB.Net
EDIT: accepted CraigTP's answer for pointing out what I currently consider the most important difference.
So to summarize: VB.Net 9 does not support multiline statements in a lambda expression, and a lambda must always return a value. Both of these issues are addressed in VB.Net 10
I wish to incorporate general expressions in my Visual Basic work.Other than the basic inputting "Imports System.Text.RegularExpressions", I have no idea how to do put general expressions in my VB project.However, I can create the expressions (so, all is not lost).
View 1 RepliesThe expression 3>6 AndAlso 7>4 evaluates to
A. True B. False
The expression 4>6 OrElse 10<2*6 evaluates to
A. True B. False
The expression 7>=3+4 OrElse 6<4 AndAlso 2<5 evaluates to
A. True B. False
Async Sub like this: Dim f As Func(Of Task) = Async Sub() End Sub Produces compiler error: error BC36670: Nested sub does not have a signature that is compatible with delegate 'System.Func(Of System.Threading.Tasks.Task)'.Equivalent C# code compiles fine:
Func<Task> f = async () => { };Rewriting Async Sub into Async Function make code works.
Why does Async Sub() is not convertible to delegate types with return value of type Task?
i need a regular expressions string to get all anchor tags in a page with a specific css class name, in c#/vb.netthis is what i got so far"<a.*?href=""(.*?)"".*?>(.*?)</a>"ut my attempts to add "class=name" isnt working, also is it possible to find links where the class name appears either before or after the href with one expression
View 4 Replieshow to convert this code to VB.net, can anybody help?
public static readonly DependencyProperty CommandProperty =
DependencyProperty.RegisterAttached(
"Command",
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I am looking for a way to simplify algebraic expressions in VB.NET. It is preferred if you can give me a link to a pre-written library or class.
View 1 RepliesI am new to VisualBasic and trying to learn it online. For my first assignment I have to make a program that allows someone to input a time in AM/PM and select the time zone and automatically output a picture and three other time zones. I think I have it for the most part but I am having an issue with one part in particular. Since the time is input using AM or PM if the original time is 11:00 AM and I add an hour it should switch to PM. But I'm not quite sure what I'm doing wrong. I basically need to say If the time is equal to 12 and the meridiem is equal to am then it should switch to pm but I keep getting errors inidicating they are trying to switch to a boolean value.
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I'm in a Collage VB.Net Class and I was wondering if it is possible to make an array of expressions like : Dim exps() = { 5*4,2+3,5*2}.
View 3 RepliesThe following works in vb.net, and basically only allows characters on a standard US Keyboard. Any other character pasted gets deleted. I use the following regular expression code:
"[^A-Za-z0-9[{}]`~!@#$%^&*()_-+=\/:;'""<>,.|? ]", "")
I have a List(of T) where T has a property that is a list of checkboxes, what I need is a Lambda expression that will count all the checked checkboxes in the list. I tried with:
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I'm trying to do is some password validation. It needs to have at least 1 lower case character, 1 uppercase character, 1 number and at least 6 characters in length. I figured I could do this using "RegularExpressions" however I can't figure out how to determine the "at least one occurance" of each. For example I thought the following would work but it only validates that what is input is a lower case, uppser case or numeric character, not that the input has at least one of each. The user should be able to enter any characters but at least one of lower case, upper case and numeric characters.
Dim
myMatch
As
Match
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I have a string list which has hundrens of elements. Now I want to find a rule to distinguish them according to their similarity. There are these kinds of pattern.
Group 1: "ABC 20", "ABC 20 Dup". There is a substring "DUP" in the last position.
Group 2: "saliva 4", "saliva 4_2","siliva 4_3", etc. There is a substring "_" plus a number in the last position.
Group 3: "sal_1", "sal_1b","sal_1c", etc. There is a character in the last popsition.
Group 4: "NA222", "NA222b", there is a character in the last position.
Group 5: "1","1_2","10","10_2" etc.
I want to put them into a dictionary if they are similar.
I have a number that always will be in this format
1815131217 Lets say I want to parse out all the 1's in between leaving only 85327
How can I do that?
What if my number is 1310111512
The number needs to be 30152 How can I do that?
I've read a fair number of articles and all tell me this is correct code. However, no matter how many e-mails I try, this always returns false:
vb
If Regex.IsMatch(txtbxFbUsername.Text, "^[A-Z0-9._%+-]+@[A-Z0-9.-]+.[A-Z]{2,4}$") = False Then
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Where is the regular expressions documentation?
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