#102: Hash Tables in Powershell

In PowerShell, a hash table, also known as an associative array or dictionary in other programming languages, is a collection of key-value pairs. Hash tables allow you to store and retrieve data efficiently based on keys rather than numerical indexes. Here's a detailed guide on how to use hash tables in PowerShell:

Creating a Hash Table:

You can create a hash table using the @{} syntax:

Example: 

$hashTable = @{

    Key1 = "Value1"

    Key2 = "Value2"

    Key3 = "Value3"

}

Accessing Values:

You can access values in a hash table by specifying the key:

Example:

$value = $hashTable["Key1"]

Adding or Modifying Values:

You can add or modify values in a hash table by assigning a value to a key:

$hashTable["Key4"] = "Value4"

$hashTable["Key2"] = "NewValue2"

Removing Values:

You can remove a key-value pair from a hash table using the Remove() method:

$hashTable.Remove("Key3")

Checking if a Key Exists:

You can check if a key exists in a hash table using the ContainsKey() method:

if ($hashTable.ContainsKey("Key1")) {

    Write-Output "Key1 exists in the hash table."

}

Iterating Over a Hash Table:

You can iterate over a hash table using a foreach loop:

foreach ($key in $hashTable.Keys) {

    $value = $hashTable[$key]

    Write-Output "$key: $value"

}

Using Hash Tables as Parameters:

You can use hash tables to pass named parameters to functions or cmdlets:

function Test-Function {

    param (

        [string]$Name,

        [int]$Age

    )

    Write-Output "Name: $Name, Age: $Age"

}

$params = @{

    Name = "John"

    Age = 30

}

Test-Function @params

Nested Hash Tables:

You can have nested hash tables to represent more complex data structures:

$nestedHashTable = @{

    Key1 = @{

        NestedKey1 = "Value1"

        NestedKey2 = "Value2"

    }

    Key2 = @{

        NestedKey3 = "Value3"

        NestedKey4 = "Value4"

    }

}

Hash tables are versatile data structures in PowerShell and are commonly used for configuration settings, organizing data, passing parameters, and more. Understanding how to work with hash tables effectively is essential for PowerShell scripting.

Hope you enjoyed this article. 

Thanks!