is there a way to supress the return value (=Index) of an ArrayList in Powershell (using System.Collections.ArrayList) or should I use another class?
$myArrayList = New-Object System.Collections.ArrayList($null)
$myArrayList.Add("test")
Output: 0
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While all options presented here are valid, I personally go for [void] for one simple reason: The need for speed :) Measure-Object is your friend. (There is a good blog article about speed for these things, but I can't find it at the moment, sorry)DEberhardt– DEberhardt2020-08-31 15:37:41 +00:00Commented Aug 31, 2020 at 15:37
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2 Answers
You can cast to void to ignore the return value from the Add method:
[void]$myArrayList.Add("test")
Another option is to redirect to $null:
$myArrayList.Add("test") > $null
3 Comments
TylerH
I've discovered the problem with either of these is that it can't be outputted (e.g.
Write-Output) when part of an existing sequence. E.g. I have an arraylist $ADUsersList that I add a record to via .Add(). When I then try to Write-Output $ADUsersList as part of the script, it's blank in my IDE. But as soon as the script is done running, and I just check $ADUsersList for contents, they get printed as I would expect.
Keith Hill
I think you have some other issue going on. Try this in PS >= 5 and you'll see it outputs the contents of the list:
$l = [System.Collections.ArrayList]::new(); $l.Add("test") > $null; $lTylerH
You're right; that does work. Not sure what about my situation is causing the difference (I'm inserting an ordered PSObject record into an ArrayList via
[void]$ArrayList.Add($objRecord). It worked if I checked $ArrayList after the script ran, but during the script any Write-Output attempts at displaying $ArrayList's contents failed). Anyway, glad to see I was mistaken. It means debugging w/ ArrayLists is slightly easier than I thought.Two more options :)
Pipe to out-null
$myArrayList.Add("test") | Out-Null
Assign the result to $null:
$null = $myArrayList.Add("test")
3 Comments
AlwaysQuestioning
Can you speak to the efficiency of piping to Out-Null versus > $null, or assigning to $null versus casting to [void]? Which of these four is most efficient?
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ListenSoftware Louise Ai Agent
why does arraylist add nulls in the list