Store AD Computer Names in an Array

Question

A fairly basic script - searches Ou in AD and exports computers - I want to store each computer into an array so I can loop through later and run some commands against the computers. Although not having much luck with the array itself - am I completely off the track here?

$computers = @()
$i = 0
$ou = [ADSI]"LDAP://OU=Domain Controllers,DC=test,DC=local"
foreach ($child in $ou.psbase.Children) {
    if ($child.ObjectCategory -like '*computer*') { 
        Write-Host $child.Name 
        $computers[$i] = $child.name
        }
    $i += 1
}

Answer 1

You're indexing into an empty array with $computer[$i]. If you don't know how big the array should be but you know it won't be huge, change to this:

$computers += $child.Name

If you know the size then allocate the array that size like so:

$computers = new-object string[] $arraySize

Then you can index into the array up to size - 1.

If you don't know the size and think it will be large, use a list instead e.g.:

$computers = new-object system.collections.arraylist
[void]$computers.Add($child.Name)

Answer 2

Use a pipeline, filter the objects with Where-Object (alias ?), and output the names in a ForEach-Object loop (alias %). The result is either an array of names or $null (when the LDAP query did not return any computer objects).

$ou = [ADSI]"LDAP://OU=Domain Controllers,DC=test,DC=local"
$computers = $ou.PSBase.Children |
             Where-Object { $_.ObjectCategory -like '*computer*' } |
             ForEach-Object { $_.Name }

If you want the result to be an empty array when no computer objects are found, wrap the command pipeline in @():

$computers = @($ou.PSBase.Children | ...)