PowerShell: Array

By Xah Lee. Date: . Last updated: .

Array is a list of values. the values can be the same type or different types.

Create Array (the comma operator)

it can be created by values separated by comma 

$x = 3, 4, 5

items can be different types:

$x = 3, "abc", 5

can be multiple lines:

$x =
"a",
"b",
"c";

$x.foreach({ echo $_ })

WARNING: Last item must not have comma. And best to add a SEMICOLON at the end. This is a frequent error if you write PowerShell script.

Create a Array of Single Item

To create a array of single item, precede the item by a comma.

$a = ,4

or use the Array Sub-Expression Operator @(...) (Collection to Array) 

$x = @(4)

Create Array by Array Sub-Expression Operator

Create Array by Range Operator

min..max
(the range operator.) Creates an array of contiguous integers, from min..max, inclusive. 
$a = 3..7
# result 3 4 5 6 7

length

use method length or its alias count

(3,4,5).length -eq 3

get items

get one item

$x = 3,4,5
$x[2] -eq 5

get a multiple items

# get index 3 and 6
(0,1,2,3,4,5,6,7)[3,6]
# (3,6)

Get a slice

$x = 0,1,2,3,4,5,6,7
$x[3..6]
# result is 3,4,5,6

Get multiple slices

use + inside [] between slices, to get different items.

$x = 0..99

# get array from index 1 to 10 and 30 to 40
$x[1..10 + 30..40]

set item

$x = 1, 2, 3
$x[0] = "b"
$x
# b 2 3

or use method SetValues(val, index)

$x = 1, 2, 3
$x.SetValue("b",0)
$x

Append an Item

Use operator += to add a item to end of array.

Note, the array data structure is optimized for not changing size. It has to recreate the array and is slow. The more items in a array, the slower it is to change size.

$x = 1, 2, 3
# add a item "b" to the end
$x += "b"
$x

delete item

It's not easy to delete array item in PowerShell. Array data structure is not designed to change size. Instead of delete, just replace the value with $null.

join arrays

use + operator.

$a = 1,2
$b = 3,4,5
$a+$b

delete array

assign the whole to $null

$a = 1,2,3
$a = $null
$a

Iterate Over Array

reset all items

array.Clear() Sets all item values to the default value of the array's item type.

$aa = 1, 2, 3
$aa.Clear()

filter array

Array to String

# array to string
[string] @(1, 2, 3) -eq "1 2 3"
# make sure last string ends semicolon, not comma
$x= @(
"abc",
"def",
"ghi"
)

($x -join ";") -eq "abc;def;ghi"

PowerShell: Array