Store output of ForEach into array in powershell

Question

$data = @("server1","server2","server3")

foreach ($server in $data) {
    $results = (Test-Connection $server -count 1 | Measure-Object -Property ResponseTime -Average).Average
}

I'm trying to figure out how to take the output of a ForEach and store the results into an array so I may then compare them later. I could not come up with a way to do this yet.

@PetSerAl, whats the difference between $results = @( foreach ...) and $results = foreach ..., doesn't it return array anyway? also, shouldn't foreach return something, for this to work? — 4c74356b41
– 4c74356b41, Commented Feb 7, 2017 at 17:57
@4c74356b41 @() always return array. Even in case of zero or one item. — user4003407
– user4003407, Commented Feb 7, 2017 at 17:59
@4c74356b41 It helps by eliminating special case, when with zero items PowerShell does not return array by default. — user4003407
– user4003407, Commented Feb 7, 2017 at 18:17

Ajay Pawar · Accepted Answer · 2017-02-08 09:32:36Z

3

    $FinalResult = @()
    $data = @("server1","server2","server3")
    foreach ($server in $data) {
        $results = (Test-Connection $server -count 1 | Measure-Object -Property ResponseTime -Average).Average

        $FinalResult += New-Object psobject -Property @{
                        ServerName = $server
                        Result = $result
                        }  
    }
   $FinalResult | Select ServerName, Result | Export-Csv ".\FinalResult.csv" -NoTypeInformation

Please let me know if this snippet doesn't work, i will do the needful.

edited Feb 8, 2017 at 9:32

answered Feb 8, 2017 at 8:34

Ajay Pawar

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1 Comment

Strill Over a year ago

This is extremely inefficient because appending creates a new array every single loop, resulting in a time complexity of O(n^2).

Myrddin Emrys · Accepted Answer · 2017-10-19 13:37:43Z

1

By doing the ForEach, you're just measuring the value of the property of a scalar (single) object. The average will always be just the value of that property.

Test-Connection will accept an array of names as the -ComputerName parameter, so the ForEach isn't really necessary at all.

 $data = @("server1","server2","server3")

 $results = Test-Connection $data -count 1 | select -ExpandProperty ResponseTime

edited Oct 19, 2017 at 13:37

Myrddin Emrys

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answered Feb 7, 2017 at 19:46

mjolinor

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2 Comments

Aaron Over a year ago

I used the example to get the concept of what I'm doing. I'm not using Test-Connection, but a more larger script, but the concept is the same. Just need to figure out how to store results into an array while having it loop until there's no more inputs.

mjolinor Over a year ago

Then you already have your answer in the comments. Simply redirect the foreach output to a variable, and Powershell will automatically build an array if it returns more than one object. You can force it to be an array using the @() syntax if that's necessary to prevent errors downstream in the case of it not returning multiple objects.

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