My co-worker said that in a previous interview, he learned that foreach is faster in VB.Net than c#'s foreach. He was told that this was because both have different CLR implementation.
Coming from a C++ perspective, I'm curious on why this is and I was told that I need to read up on CLR first. Googling foreach and CLR doesn't help me understand.
Does anyone have a good explanation on why foreach is faster in VB.Net than in c#? Or was my co-worker misinformed?
I have searched high and low for documentation on how to use this feature. While the loop I could write would be simple and take no time, I really would like to learn how to use this. Basically I have a class, say, Widget, with a Save() sub that returns nothing. So:
Dim w as New Widget() w.Save()
basically saves the widget. Now let's say I have a generic collection List(Of Widget) name widgetList(Of Widget) and I want to run a Save() on each item in that list. It says I can do a
widgetList.ForEach([enter Action(Of T) here])
....but how in the F does this work??? There is no documentation anywhere on the intrablags.
I'm writing a loop to go through the first array of a 2D loop, and I currently have it like this:
For Each Dir_path In MasterIndex(, 0) 'do some stuff here Next
But it's giving me an error, saying it expects an expression in the first field. But that's what I'm trying to do, loop through the first field. How do I fix this? What would I put in there?
EDIT: to clarify, I'm specifically looking for the 0th element in the subarray of each array, that's why that second field is constantly 0.
What i'm doing is getting values from some html, i use a regex to retrieve all the fields, but there are some fields brought back i don't need (4 out of 11) i know the names of these fields, but was wondering if there was a way i could filter out the ones i don't need in the foreach:[code]
I recently changed a For Each loop to a Parallel.ForEach loop. I'm concerned about an object being declared outside the loop but assigned while iterating in the loop. Here is the simplified code.
Dim results As ModelResults Dim noResultsModel As New List(Of ModelResults) Dim lock As New Object Parallel.ForEach(_modelEngines, Sub(model)
[Code]...
Is there a potential race condition with the results object? Would anything be different if I moved the declaration of results into the for loop?
I'm flummoxed I'm using VB.Net, Linq, and a DataContext. My DataContext contains a table 'transactions'.
I first declare an IQueryable(Of transaction) and assign it to nothing. I build a predicate in a foreach loop and use a transactions.Where(predicate) to assign the IQueryable a value. If I do an IQueryable.ToList(), I get a number of items in the collection.
However, on the next iteration of the loop, the IQueryable.ToList() gives me 0 items.This is driving me crazy. I tried to use the LINQ to SQL Debug Visualizer with VS2010, (I recompiled the 2008 version with the new reference) but no dice - I can't see the SQl generated or what's inside the IQueryable.
I am making a program that automates the seperation of a csv file. We read the csv in through and then assign the "line" using a split command to an array. After that we go through each "cell" in the array and put an = in front because this causes leading zeros not to be lost. Here's the code.
arLine = line.Split(replace) For Each cell As String In arLine cell = cell.Replace(",", "") cell = String.Format(cellFormat, cell) Next
arLine is the array and replace is the delimiter, in this case a pipe not that it matters.'
When it goes through, the arLine is correct but the values in each cell are not changing, any thoughts? newer to VB.net and need direction
I am having an issue extracting the value from every row in column "MobileID" within a table named "dt" that is within a dataset named "ds".Here is how the dataset and datatable are created.[code]
I have the following for each loop which loops through a registry key and reads all the values:
Dim returnValue As RegistryKey = Registry.LocalMachine.OpenSubKey("SOFTWAREMicrosoftWindowsCurrentVersionRun") Dim keyname As String = "HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun" Dim values() As String = returnValue.GetValueNames
[code].....
What I am trying to have been highlighted in bold.. Each time the loop executes and reads a value from the registry, I want the code to create a checkbox which has a unique name and text according to the value that was read... So the number of checkboxes will depend on number of values that is got from the registry...But this doesn't work. It only creates one text box and the text of the textbox is also incomplete...
Everything is working fine except for one part. The part where the second foreach loop runs. If I only have one plugin installed it puts 2 entries in the list. The reason is because it has 2 rows and it is adding it twice. I know what the issue is I just am drawing a blank right now.
I've been trying to follow the examples I've found online and, well, I can't really get my head around what I've done wrong.So, I have a simple piece of code to search for a machine in AD, as so. [code]
I can't seem to get the syntax right for a simple Parallel.Foreach Loop.
This is how I would normally iterate a SearchResultCollection
Dim src As SearchResultCollection = DSearch.FindAll For Each x As SearchResult In src Debug.WriteLine(GetProperty(x, "Name")) 'Parallel.ForEach(x, Function(x) Debug.WriteLine(x)) Next
As I have (obviously) misunderstood it this should be the syntax for the Parallel.Foreach
Parallel.ForEach(src, (Sub(x As SearchResult) GetProperty(x, "Name"))) Parallel.ForEach(src, Function(x) Debug.WriteLine(x)) It's not that though. What's the correct syntax here?
I have a form called frmMapViewer. In this form I 25 labels showing districts of my country. think I want to assign names(text property) to each label.[code]...
Why there is only a static/shared version of ForEach for arrays? IE: ForEach<T>(T array[], System.Action(Of T) action[]) I assume this has something to do with the type inference requirements of implementing an instance method, but when you declare your array you provide type right?
How to write xml foreach datarow in dataset? I have dataset with 5 record in table, i want write to xml file with 5 xml file. in one xml file have one record.
This is weird. I have a class that inherits from IEnumrable whose Count property is reporting 0 (zero) elements but the For Each loop steps into the loop body and tries to use the variable where it should just be moving on. My code:
On Error Resume Next Dim d As Foo For Each d In fooCollection ' use d and throws an exception Next d
Weirder still, every time d is accessed i get an exception thrown in the output window:
A first chance exception of type 'System.NullReferenceException'
but i'm not stopping on the exception (not in a try/catch block).Is "On Error Resume Next" causing this weirdness?
Weirdness found:Per Rowland's and JohnH's comments i checked the Foo class:The GetEnumerator method inside of Foo didn't actually return anything! It had an empty body. That coupled with the On Error Resume Next before the loop caused the havoc! Wow this was ugly.
I am using Parallel.ForEach to do some time consuming operation. Coming to the question ,
For example,
I am enumerating a collection called 'TestCollection' which has 3 items.
Parallel.ForEach(TestCollection, po, AddressOf DoSomeThing) So 3 tasks will be running in paralell at a time Now I want to add another 2 items to TestCollection, while the task is running.
How to enque the additional 2 items to the 'TestCollection' so that additional two tasks will also run in paralell. Finally 5 tasks should run in paralell without stopping the running task. If a post answers your question,
When i parse some html and get the fields i need using regex, the first 4 fields returned are fields i don't need, so essentially i need all fields returned after the 4th one.
vb.net '// First piece of data we want... Dim stringID As New Regex("(?<=><optionvalue="").*?(?="">)", _ RegexOptions.IgnoreCase Or RegexOptions.Singleline) Dim stringsMatched As MatchCollection = stringID.Matches(stringClean)
[CODE]...
Is there a way i can blank out the first 4 fields returned?
I have a custom list that inherits Generic.List and it has a method for deselecting all of the members named DeselectAll It has looked like this for a few weeks and has worked fine.
Public Sub DeselectAll() MyBase.ForEach(Function(p As Publipostable) p.ModeEnvoiChoisi = Nothing) End Sub
Today, it stopped working ?!? I reverted to an earlier version using delegates and that works fine...
Public Sub DeselectAll() MyBase.ForEach(AddressOf DeselectModeEnvoi) End Sub
[code]....
Edit: Stopped Working meaning it no longer sets the property p.ModeEnvoiChoisi to Nothing on each item in the list. The DeselectAll method gets called, but all the items retain their previous values...
However it always returns 0. I've checked and the GetPartCost function executes and returns a non-zero number but the list item cost properties are never updated.The property is just a simple property,
Public Property Cost() As Double Get Return _Cost[code]....
If I set a breakpoint in the Set of the property, it never gets hit.
Here's the code I have but I'm getting syntax issues:
CODE:
I'm just looking to call ReadAndPopulate method for each item in aList. I know I can do it the traditional "For each a in aList...Next" way but wanted to learn how to do it with delegates.
