Function return array in PowerShell

Question

I have a problem when I'm trying to return an array from a PowerShell function.

My function:

function filter-SWCluster {
   param($Path, $FolderList)
   $OldSWCluster = New-Object System.Collections.ArrayList
   ForEach ($y in $FolderList) {
      Get-ChildItem -Path $Path -Filter $y* | sort { [version]($_.Name -replace '^.*_(\d+(\.\d+){1,3})$', '$1') } -Descending | Select-Object -skip 3 | ForEach-Object { $OldSWCluster.Add($Path + "\" + $_) }
   }
   Write-Output $OldSWCluster
}

The function call:

$FilerSWCluster = filter-SWCluster $NetworkPath $SWCluster

The output I get:

0 1 \\server.domain\C$\TEMP\Folders\Testcluster_1.0.2 \\server.domain\C$\TEMP\Folders\Testcluster_1.0.1

The output I want and need would be:

\\server.domain\C$\TEMP\Folders\Testcluster_1.0.2 \\server.domain\C$\TEMP\Folders\Testcluster_1.0.1

I need just the paths. I know there will already be some solutions, but please excuse me. I didn't find one which was working for me or I were to dumb to use it right (could be).

ArrayList's Add method returns the new index, you need to hide it e.g. $OldSWCluster.Add($Path + "\" + $_) >$null — woxxom
– woxxom, Commented Nov 10, 2016 at 9:15
Man you are great, it worked perfectly. Did I understood right, the add method is not just adding the value, its also adding an index. And when I'm passing back the variable, the index get passed too? — Anetair
– Anetair, Commented Nov 10, 2016 at 10:20
1) it adds just the value into the array and 2) emits the index into the default output stream by using implicit Write-Output, which can be suppressed by redirecting to $null or casting to [void] as the other answer shows. — woxxom
– woxxom, Commented Nov 10, 2016 at 10:25

Peter Mortensen · Accepted Answer · 2019-06-26 20:52:32Z

5

You could also wrap the Add method with the [void] class accelerator. It will hide any output, like this:

function filter-SWCluster {
   param($Path, $FolderList)
   $OldSWCluster = New-Object System.Collections.ArrayList
   ForEach ($y in $FolderList) {
      Get-ChildItem -Path $Path -Filter $y* | sort { [version]($_.Name -replace '^.*_(\d+(\.\d+){1,3})$', '$1') } -Descending | Select-Object -skip 3 | ForEach-Object { [void]$OldSWCluster.Add($Path + "\" + $_) }
   }
   Write-Output $OldSWCluster
}

edited Jun 26, 2019 at 20:52

Peter Mortensen

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answered Nov 10, 2016 at 9:43

Kirill Pashkov

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Comments

Peter Mortensen · Accepted Answer · 2019-06-26 20:53:16Z

2

wOxxOm already provided you a solution to your problem. However, consider to just return the path using a simple select. You also don't have to join the path since the FullName property already contains the full path:

function filter-SWCluster {
   param($Path, $FolderList)
   ForEach ($y in $FolderList) {
      Get-ChildItem -Path $Path -Filter $y* |
        sort { [version]($_.Name -replace '^.*_(\d+(\.\d+){1,3})$', '$1') } -Descending |
        Select-Object -skip 3 |
        select -ExpandProperty FullName
   }
}

edited Jun 26, 2019 at 20:53

Peter Mortensen

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answered Nov 10, 2016 at 9:21

Martin Brandl

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1 Comment

Anetair Over a year ago

Thanks would also be an opportunity, but I cant implement it in my script like this.

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