PowerShell

Output Behavior

• Everything not captured goes to output — even without return or Write-Output
• return doesn't stop output — previous uncaptured expressions still output
• Write-Host bypasses pipeline — use for display only, not data
• Assign to $null to suppress — $null = SomeFunction
• [void] cast also suppresses — [void](SomeFunction)

Array Gotchas

• Single item result is scalar, not array — @(Get-Item .) forces array
• Empty result is $null, not empty array — check with if ($result) carefully
• Array unrolling in pipeline — @(1,2,3) | ForEach sends items one by one
• += on array creates new array — slow in loops, use [System.Collections.ArrayList]
• , is array operator — ,$item wraps single item in array