PowerShell Remove item [0] from an array

Question

I'm struggling a bit to remove the first line (item ID) of an array.

$test.GetType()  IsPublic IsSerial Name                                     BaseType                                                                                                       -------- -------- ----                                     --------                                                                                                       True     True     Object[]                                 System.Array 

To list all the options I tried ,$test | gm and it clearly states:

Remove         Method                void IList.Remove(System.Object value)                                                                                               RemoveAt       Method                void IList.RemoveAt(int index) 

So when I try $test.RemoveAt(0) I get the error:

Exception calling "RemoveAt" with "1" argument(s): "Collection was of a fixed size."At line:1 char:1 + $test.RemoveAt(1) + ~~~~~~~~~~~~~~~~~     + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException     + FullyQualifiedErrorId : NotSupportedException 

So I finally found here that my array needs to be of the type System.Object to be able to use $test.RemoveAt(0). Is it best practice to declare all the arrays in the beginning of the script as a list? Or is it better to convert the arrays with $collection = ({$test}.Invoke()) to a list later on when this functionality is needed?

What are the pro's and cons of both types? Thank you for your help.

Answer 1

An alternative option is to use Powershell's ability to assign multiple variables (see this other answer).

$arr = 1..5 $first, $rest= $arr  $rest 2 3 4 5 

It's been a feature of Powershell for over a decade. I found this functionality from an MSDN blog post:

Answer 2

Arrays are fixed-size, like the error says. RemoveAt() is an inherited method that doesn't apply to normal arrays. To remove the first entry in the array, you could overwrite the array by a copy that includes every item except the first, like this:

$arr = 1..5  $arr 1 2 3 4 5  $arr = $arr[1..($arr.Length-1)]  $arr 2 3 4 5 

If you need to remove values at different indexes then you should consider using a List. It supports Add(), Remove() and RemoveAt():

#If you only have a specific type of objects, like int, string etc. then you should edit `[System.Object] to [System.String], [int] etc. $list = [System.Collections.Generic.List[System.Object]](1..5)  $list 1 2 3 4 5  $list.RemoveAt(0)  $list 2 3 4 5 

See my earlier SO answer and about_Arrays for more details about how arrays work.