How to Use Hashtable in PowerShell: Syntax and Examples

In PowerShell, a hashtable is a collection of key-value pairs created using @{} syntax. You add items by specifying keys and values inside the braces, and access values by their keys using $hashtable['key'].

Syntax

A hashtable in PowerShell is defined using @{} with key-value pairs inside. Each key is followed by an equals sign and its value. You can access values by using the key inside square brackets after the hashtable variable.

• @{}: Defines the hashtable.
• key = value: Adds a key-value pair.
• $hashtable['key']: Retrieves the value for the key.

powershell

$hashtable = @{ Key1 = 'Value1'; Key2 = 'Value2' }
$value = $hashtable['Key1']

Example

This example shows how to create a hashtable, add key-value pairs, and access a value by its key.

powershell

$person = @{ Name = 'Alice'; Age = 30; City = 'Seattle' }
Write-Output $person['Name']
Write-Output $person['Age']

# Adding a new key-value pair
$person['Occupation'] = 'Engineer'
Write-Output $person['Occupation']

Output

Alice
30
Engineer

Common Pitfalls

Common mistakes include using parentheses instead of braces to create a hashtable, forgetting quotes around string keys when accessing values, or trying to access keys that do not exist.

Always use @{} to create hashtables, and use quotes around keys when accessing values if the key is a string.

powershell

# Wrong: Using parentheses instead of braces
$wrong = ( Key = 'Value' ) # This creates a different object, not a hashtable

# Right: Use braces
$right = @{ Key = 'Value' }

# Wrong: Accessing key without quotes (works only if key is a valid variable name)
$value = $right[Key] # May cause error or unexpected result

# Right: Use quotes
$value = $right['Key']

Quick Reference

Remember these quick tips when working with hashtables in PowerShell:

• Use @{} to create a hashtable.
• Keys are case-insensitive strings by default.
• Access values with $hashtable['key'].
• Add or update keys by assignment: $hashtable['newKey'] = 'newValue'.
• Use GetEnumerator() to loop through all key-value pairs.

Key Takeaways

Create hashtables using @{} with key = value pairs inside.

Access values by keys using $hashtable['key'] with quotes around string keys.

Add or update entries by assigning a value to a key like $hashtable['key'] = value.

Avoid using parentheses instead of braces to define hashtables.

Use GetEnumerator() to loop through all keys and values in a hashtable.