.net - Action(Of T) In VB In List(Of T).ForEach?
May 21, 2009
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.
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Mar 1, 2010
I have a list like this
[Code]...
How can I iterate the list with ForEach to get one string with the emails like this [URL]
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Apr 2, 2011
I have a List(Of SomeObject) that I enumerate over using a For Each loop. This SomeObject contains a Property that references another Object, as such
Class SomeObject
Public Property Another As AnotherObject
Get
[Code]....
If not, what is a valid way to do it? (ordinary for loop perhaps?)
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Dec 16, 2010
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...
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Aug 8, 2011
I have the following code,
PB.ForEach(Function(x) x.Cost = GetPartCost(x.PartNumber, x.Units, x.Cost, FB))
Return PB.Sum(Function(x) (x.Cost * x.Qty))
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.
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Jun 29, 2011
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.
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Sep 6, 2011
Is it possible to pass multiple arguments to a delegate method from a list(Of T).ForEach call?So, I'd like to pass a listbox object to the delegate routine below:
Sub test()
Dim names As New List(Of String)
names.Add("Bruce")
names.Add("Alfred")
[code]....
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Dec 5, 2011
Looking to have a list(Of object) where i can make my own Add method, so i can do some stuff to an item when added
Is that possible at all, been looking at the net and haven't found anything.
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Jan 6, 2011
I hope this question is sufficiently clear I'm trying to port an application that I wrote in Access VBA to VB 2010 express and SQL Server. In Access, when the user enters an item in a combobox that is not in the item list an event is fired ("not in list") from which I can set up records in related tables. How can I do the same in VB? I can't see any equivalent to the "not in list" event.
To be more explicit with an example. An address consists of Street, e.g. "23 Acacia Drive", Town, e.g."Wilton" and County, e.g. "Oxfordshire". When entering a new address, the form first requires a street entry in a text box. Next, a Town entry in a combo box which is populated with towns already in the address table. If an existing Town is selected the (previously disabled) County field is automatically filled from that town's County as read from the database. If a new Town is entered the County field is enabled and the user either selects an existing County or adds a new one which is added to the database using similar logic on the not in list event.
[Code]...
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Mar 28, 2011
a datacontext defined in a module(domain services ado.net ria)a page having add/delete methods whenever any method is executed, it is found that all the previous actions (NEW RECORD ADDITION and DELETION OF RECORDS) are carried out before the new action is carried out normally
this behaviour is not prominent but "when using break points and inspecting the values of the variables and table object to be added to context, it is clear that all the previous actions take place again. even when the datacotext. savechanges is called, even after that still all actions carried out on the datacontext repeat themseleves, when any new action is to be carried out
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Mar 12, 2009
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?
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Apr 15, 2010
tell how to form this to the correct Syntax?ere the sample in sequential form:ForEach ctrl AsCheckBoxIn tblCKBoxCollection.Controlsctrl.Checked =
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May 16, 2011
I try to replace the classic For Each with the LINQ ForEach method in VB.NET
Dim singles As New List(Of Single)(someSingleList)
Dim integers As New List(Of Integer)
For Each singleValue In singles
[code]....
How should I correctly do it (using anonymous methods = without declare a new function)?
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Oct 14, 2011
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.
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Aug 24, 2010
is it possible to use foreach with a 2d array?
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Aug 30, 2009
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]
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Aug 3, 2010
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?
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Apr 15, 2012
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.
[Code]...
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Jun 13, 2012
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
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May 12, 2009
In C# i just put the method in the parentheses that i want to run on each row of the collection, but it isn't working in VB.NET.[code]...
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Apr 18, 2012
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]
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May 8, 2009
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...
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Jul 9, 2009
I have the following Method:
CODE:
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.
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Apr 16, 2010
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]
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Oct 18, 2010
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?
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Mar 9, 2009
i'm using a foreach to loop through my regular expression like:
For Each secwordMatch As Match In secwordmatches
Dim secWord As String = secwordMatch.ToString
Next
[code].....
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Apr 8, 2009
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]...
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Aug 18, 2011
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?
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Jul 29, 2011
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.
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Nov 5, 2011
I am trying change from Delegates to Parallel.ForEach I see the below works fine. Imports System.Threading.Tasks
Sub Main()
Dim secs() As Integer = {2, 3, 1}
Parallel.ForEach(secs, AddressOf Method2)
End Sub
[Code]...
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