PoshBytes: Is it Contained or In an Array?

Should you use -contains or -in in your PowerShell comparison? This PoshBytes solves the common membership test confusion by showing when something is contained versus in.

This post is a companion for the video embedded below. Scroll down to see the code from the video.

The Setup

$awesome = 'IT','DevOps','SecOps'
$awesome -contains 'IT'
'IT' -contains $awesome
$awesome -in 'IT'
'IT' -in $awesome

$users

When Something Is “Contained”

-Contains Collection first

$users | 
  Where-Object { $awesome -contains $_.Department }

When Something Is “In”

-In Value first

$users | 
  Where-Object { $_.Department -in $awesome }

Use in logic operations

Ordering remains the same in logic operations

$users | ForEach-Object {
  if ($awesome -contains $_.Department) {
    Write-Host "Awesome: $($_.Name)" -F Green
  }
  else{
    Write-Host "Not Awesome: $($_.Name)" -F Red
  }
}

Not Contains and In

Not order stays the same but return logic is reversed

$users | ForEach-Object {
  if ($_.Department -notin $awesome) {
    Write-Host "Sorry: $($_.Name) :("
  }
}

Wrap Up

• -contains requires the collection on the left
• -in requires the value on the left
• Both perform membership comparisons
• Match the operator to your sentence structure