PowerShell array unshift

Question

After reading this helpful article on the Windows PowerShell Blog, I realized I could "shift" off the first part of an array, but didn't know how to "unshift" or push elements onto the front of an array in PowerShell. I am creating an array of hash objects, with the last read item pushed onto the array first. I'm wondering if there is a better way to accomplish this. ``` ## Create a list of files for this collection, pushing item on top of all other items if ($csvfiles[$collname]) { $csvfiles[$collname] = @{ repdate = $date; fileobj = $csv }, $csvfiles[$collname] | %{$_} } else { $csvfiles[$collname] = @{ repdate = $date; fileobj = $csv } } ``` A couple of things to note: - I need to unroll the previous array element with a foreach loop %{$_}, because merely referencing the array would create a nested array structure. I have to have all the elements at the same level. - I need to differentiate between an empty array and one that contains elements. If I attempt to unroll an empty array…

Accepted Answer

You might want to use ArrayList objects instead, as they support insertions at arbitrary locations. For example:

```
# C:\> $a = [System.Collections.ArrayList]@(1,2,3,4)
# C:\> $a.insert(0,6)
# C:\> $a
6
1
2
3
4
```

PowerShell array unshift

Solution

Problem