Courses/PowerShell/Variables and Data Types

Variables and Data Types

Store strings, numbers, arrays, and hashtables in PowerShell variables.

Our editor simulates PowerShell output using JavaScript. For real practice, open PowerShell on your system.

What You'll Learn

Creating and using variables with the $ prefix
String interpolation (double vs single quotes)
Arrays, hashtables, and ordered hashtables
Automatic variables: $_, $null, $HOME, $Error

Variables and Types

In PowerShell, variables start with $ and are dynamically typed — you don't declare a type, PowerShell figures it out. Under the hood, every variable is a .NET object.

$name = "Alice"          # System.String
$age = 30                # System.Int32
$price = 19.99           # System.Double
$isAdmin = $true         # System.Boolean
$nothing = $null         # Null

String interpolation is one of the most important features. Double-quoted strings expand variables; single-quoted strings are literals:

"Hello, $name!"      → Hello, Alice!
'Hello, $name!'      → Hello, $name!
"2 + 2 = $(2 + 2)"  → 2 + 2 = 4     (subexpression)

⚠️ Common Mistake

Using single quotes when you want interpolation: 'User: $name' prints the literal text $name. Always use double quotes for variable expansion.

Variables & Types

Explore PowerShell variables, types, and string interpolation.

Try it Yourself »

JavaScript

// PowerShell Variables — simulated in JavaScript
console.log("=== Variables in PowerShell ===");
console.log();
console.log("Variables start with $ and are dynamically typed:");
console.log();

// Simulate PS variables
let name = "Alice";
let age = 30;
let isAdmin = true;
let scores = [95, 87, 92, 88];

console.log('  $name = "Alice"       → String: ' + name);
console.log("  $age = 30             → Int32: " + age);
console.log("  $isAdmin = $true      → Boolean: " + isAdmin);
console.log("  $sc
...

Collections: Arrays & Hashtables

Arrays store multiple values. Create them with @() syntax:

$colors = @("Red", "Green", "Blue")
$colors[0]       # Red
$colors[-1]      # Blue (last)
$colors += "Yellow"  # Add item (creates new array!)

Hashtables are key-value pairs (like dictionaries). Use @{}:

$server = @{
    Name   = "WebServer01"
    IP     = "192.168.1.10"
    Status = "Running"
}
$server.Name          # WebServer01
$server["IP"]         # 192.168.1.10
$server.Port = 8080   # Add new key

Use [ordered]@{} when key order matters — regular hashtables don't guarantee order.

Collections

Work with arrays, hashtables, and automatic variables.

Try it Yourself »

JavaScript

// Arrays & Hashtables — simulated in JavaScript
console.log("=== Arrays ===");
console.log();

let fruits = ["Apple", "Banana", "Cherry"];
console.log("  $fruits = @('Apple', 'Banana', 'Cherry')");
console.log("  $fruits[0]      → " + fruits[0]);
console.log("  $fruits[-1]     → " + fruits[fruits.length - 1] + "  (last item)");
console.log("  $fruits.Count   → " + fruits.length);
console.log();

// Adding to array
fruits.push("Date");
console.log("  $fruits += 'Date'  → [" + fruits.join(", ") +
...

💡 Pro Tip

For large collections that grow frequently, use [System.Collections.ArrayList] instead of @(). The += operator on arrays creates a brand-new array each time, which is O(n) — ArrayList's .Add() is O(1).

📋 Quick Reference

Type	Syntax	Example
String	"text"	$name = "Alice"
Integer	42	$count = 42
Boolean	$true/$false	$ok = $true
Array	@()	$arr = @(1,2,3)
Hashtable	@{}	$h = @{A=1}

🎉 Lesson Complete!

You can now work with variables, strings, arrays, and hashtables. Next up: understanding PowerShell's powerful object pipeline.