PowerShell Array Guide

In real-time application requirements, we will work with a custom PowerShell object array (complex object) instead of a simple string or integer array. The Unique switched parameter can also be used to find distinct objects by a property in a custom object array.

# Initialize the array
$Array = @()
 
$Array += [PSCustomObject]@{ Name = "User1"; }
$Array += [PSCustomObject]@{ Name = "User2"; }
$Array += [PSCustomObject]@{ Name = "User2"; }
$Array += [PSCustomObject]@{ Name = "User3"; }
 
$ResultArray = $Array | Select-Object -Unique -Property Name
  
$ResultArray # Result array with unique Name values
  
Name
----
User1
User2
User3

As already explained, the Unique parameter with Select-Object cmdlet finds unique values with case-sensitive string comparison. If you work with a string property and want to perform a case-insensitive string comparison to find distinct objects, then we need to use the Unique parameter with Sort-Object cmdlet to perform a case-insensitive check.

# Initialize the array
$Array = @()
 
$Array += [PSCustomObject]@{ Name = "User1"; }
$Array += [PSCustomObject]@{ Name = "user2"; }
$Array += [PSCustomObject]@{ Name = "User2"; }
$Array += [PSCustomObject]@{ Name = "User3"; }
 
# Find unique objects by case-sensitive comparison.
$Array | Select-Object -Unique -Property Name
  
Name
----
User1
user2
User2
User3 
  
# Find unique objects by case-insensitive comparison.
$Array | Sort-Object -Unique -Property Name 
  
Name
----
User1
User2
User3

There are three methods to create and define an array. Based on these three methods, below are the three syntaxes of a PowerShell array:

In the first syntax, an array is created by enclosing the items in the @() parentheses.

$ArrayList = @('item 1', 'item 2', 'item 3')

The second syntax creates an array with items in a comma-separated list.

$ArrayList  = 'item 1', 'item 2', 'item 3'

The third syntax creates an array with a specific data type.

[ArrayType[]]$ArrayList = 'item 1', 'item 2', 'item 3'

To access an item in an array we can use an index.

$ArrayList = @('item 1', 'item 2', 'item 3')
$ArrayList [1]
item 2