Powershell array ignorance

Question

'scuse my ignorance... I use @($var).Count so I can get a count even if $var contains 1 "item". When my search returns nothing why does my array contain one item? i.e.

  PS C:\Windows\system32> $Groups = $null

    Import-Module -Name "activedirectory"

    $search = "aaaarggg"

    $searchPat = `"*"` + $search + `"*"`

    $Groups = Get-ADGroup -Filter {(name -like $searchPat)}

    if ($Groups -eq $null) {
        "No matches"
        @($Groups).Count
    }
    else {
        "Matches"
        @($Groups).Count
    }



 No matches

    1

Because you are creating an array with a single element - null. — Lee
– Lee, Commented Dec 5, 2013 at 9:08

nohwnd · Accepted Answer · 2013-12-05 10:21:01Z

2

As Lee said you create array which contains one item and the item is null. It may seem illogical, but it is done this way to give you consistent results when decrementing or incrementing the amount of items in the array. Look at the example below. If the @($null).count returned 0 you would jump from 2 to 0.

@($null,$null,$null).Count #output 3
@($null,$null).Count #output 2
@($null).Count #output 1
@().Count #output 0

Ingoring $null values inside the @() operator would also render such situations impossible to handle:

$("a",$null,"c").count #output 3
$("a","b","c").count #output 3

answered Dec 5, 2013 at 10:21

nohwnd

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Comments

Vish · Accepted Answer · 2013-12-05 09:08:31Z

0

From the Powershell doc You create an empty array as $a = @()

To count the elements you can simply do $a.Count

$x = @()
$x.Count
0

As for processing the results of Get-ADGroup, that depends on what it returns. I think you'll find that simply doing if ($Groups.Count -eq 0 ) { # process } will work for you.

answered Dec 5, 2013 at 9:08

Vish

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