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Variables and Data Types

In PowerShell, variables are storage containers for data. Every variable name starts with a $ sign, and you create one simply by assigning a value to it.

Creating and Assigning Variables

powershell

$name = "Alice"
$age = 30
$isAdmin = $true

No declaration keyword is needed — variables spring into existence on first assignment. Variable names are case-insensitive, so $Name and $name refer to the same variable.

Key Concept: PowerShell uses automatic type detection. When you assign 42, the variable becomes an [int]. Assign "hello", and it becomes a [string]. You can check a variable's type with .GetType().

powershell

$count = 42
$count.GetType().Name   # Int32

$count = "hello"
$count.GetType().Name   # String

Common Data Types

| Type | Example |

|--------------|----------------------------------|

| [string] | "Hello World" |

| [int] | 42 |

| [bool] | $true, $false |

| [array] | @(1, 2, 3) |

| [datetime] | Get-Date |

Type Casting

You can force a variable to a specific type by placing the type accelerator before the variable name or the value:

powershell

[int]$port = "8080"          # converts string "8080" to integer 8080
[string]$code = 404          # converts integer 404 to string "404"
[datetime]$date = "2025-01-15"  # converts string to DateTime object

Once a variable is constrained with a type, it rejects incompatible values:

powershell

[int]$number = 10
$number = "hello"   # Error — "hello" cannot convert to int

The $null Value

$null represents the absence of a value. Any variable that has never been assigned is $null:

powershell

$undefined -eq $null   # True

Key Concept: Always place $null on the left side of comparisons ($null -eq $var) to avoid unexpected behavior when $var is an array.

Use $null to explicitly clear a variable:

powershell

$data = "something"
$data = $null   # variable now has no value

Exercises

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Create a variable called $greeting and assign it the value "Hello, World!".

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