Arrays

An array holds an ordered list of values.

$fruits = 'apple', 'banana', 'cherry'
$fruits[0]
$fruits[-1]
$fruits.Count
$fruits[0..1] -join ', '

$empty = @()
$empty.Count

apple
cherry
3
apple, banana
0

• A comma-separated list creates an array; @() creates an empty one (or forces a result to be an array).
• Indexes start at 0; negative indexes count from the end.
• 0..1 is a range, so $fruits[0..1] takes a slice.

Adding and removing

$fruits = @('apple', 'banana')
$fruits += 'cherry'
$fruits = $fruits | Where-Object { $_ -ne 'banana' }
$fruits -join ', '

apple, cherry

Arrays have a fixed size: += actually creates a new, bigger array each time. That's fine for small lists, but slow in a loop with thousands of items. Use a list instead:

$list = [System.Collections.Generic.List[string]]::new()
$list.Add('apple')
$list.Add('banana')
$list.Remove('apple') | Out-Null
$list.Count
$list[0]

1
banana

The easiest way to build an array

Assign a loop's output directly — PowerShell collects it into an array:

$squares = foreach ($n in 1..5) { $n * $n }
$squares -join ' '

1 4 9 16 25

One item or many?

A command that returns a single object returns that object, not an array — so .Count and indexing can surprise you. Wrap the call in @( ) to always get an array: $files = @(Get-ChildItem *.log).

Practice

Create an array of five numbers, then print the largest and the total.

$numbers = 12, 7, 31, 5, 18
($numbers | Measure-Object -Maximum).Maximum
($numbers | Measure-Object -Sum).Sum

31
73