How to Create an Array, Hash Table, and Dictionary in PowerShell

1. Use @() to Create an Array in PowerShell
2. Use the Index Number in Brackets [] Individual Access Items in an Array PowerShell
3. Create a Hash table in PowerShell
4. Create an ordered dictionary in PowerShell

Arrays are the collection of values or objects. Most programming languages have arrays as the fundamental feature.

In PowerShell, an array is simply a data structure that serves as a collection of multiple items.

Use @() to Create an Array in PowerShell

The items can be the same or different types. The proper way to create an array in PowerShell is by using @().

The items of an array are placed in the @() parentheses. An empty array will be created when no values are placed in ().

The following command creates an array $data with 3 items.

$data = @('apple', 'ball', 'cat')

Call the array variable to see items in it.

$data

Output:

apple
ball
cat

You can use the GetType method to get the data type of a variable.

$data.GetType()

Output:

IsPublic IsSerial Name                                     BaseType                                                                  
-------- -------- ----                                     --------                                                                  
True     True     Object[]                                 System.Array  

Use the Index Number in Brackets [] Individual Access Items in an Array PowerShell

You can access individual items in an array by using the index number in brackets []. The items are stored in the index number in ascending integer order starting from zero.

To get the first item in an array, you have to use [0]:

$data[0]

Output:

apple

Create a Hash table in PowerShell

A hash table is a compact data structure that stores each value using a key. It is also known as dictionary or associative array.

It is a simple key/value store. For example, a hash table might contain students’ names and roll numbers, where the students’ names are the keys and the roll numbers are values, or vice-versa.

You can create a hash table in PowerShell by using @{}. The keys and values are added in the {} brackets.

The keys and values in hash tables are .NET objects. They can have any object type.

The following command creates a hash table $hash with three keys and values.

$hash = @{Fruit = "Apple"; Color = "Red"; Count = 5 }

A hash table is displayed in the tabular format having one column for keys and another for values.

$hash

Output:

Name                           Value                                                                                                 
----                           -----                                                                                                 
Fruit                          Apple                                                                                                 
Color                          Red                                                                                                   
Count                          5

Get the data type of $hash.

$hash.GetType()

Output:

IsPublic IsSerial Name                                     BaseType                                                                  
-------- -------- ----                                     --------                                                                  
True     True     Hashtable                                System.Object

Hash tables have Keys and Values properties. You can access the items of a hash table by using the Key name as an index.

$hash['Color']

Output:

Red

Or, you can use the dot notation to display values in keys.

$hash.Count

Output:

5

Create an ordered dictionary in PowerShell

You can create an ordered dictionary using the [ordered] attribute. It would help to place the attribute before the @ symbol.

$dict = [ordered]@{Fruit = "Apple"; Color = "Red"; Count = 5 }

Ordered dictionaries can be used in the same way as a hash table.

$dict

Output:

Name                           Value                                                                                                 
----                           -----                                                                                                 
Fruit                          Apple                                                                                                 
Color                          Red                                                                                                   
Count                          5

The keys in an ordered dictionary always appear. But there is no such order of keys in a hash table.

We hope this article helps you understand how to create an array, hash table, and ordered dictionary in PowerShell.