PowerShell Data Types

A data type tells PowerShell what kind of value a variable holds — text, a number, a true/false flag, or something more complex. Knowing data types prevents calculation errors, type mismatches, and unexpected output in scripts.

How PowerShell Handles Data Types

PowerShell uses the .NET type system. Every value in PowerShell is an object, and every object has a type. PowerShell detects the type automatically when a value is assigned — this is called dynamic typing. The type can also be locked in manually — this is called static typing.

  Value Assigned        Type Detected
  ------------------    -----------------
  "Hello"          -->  [string]
  42               -->  [int]
  3.14             -->  [double]
  $true            -->  [bool]
  Get-Date         -->  [DateTime]
  @(1,2,3)         -->  [array]

Core Data Types in PowerShell

String Data Type

Strings hold text. They are enclosed in double quotes or single quotes.

[string]$firstName = "Arjun"
[string]$lastName  = "Sharma"

# Concatenate strings
$fullName = $firstName + " " + $lastName
Write-Host $fullName

# String length
Write-Host $fullName.Length

# Convert to uppercase
Write-Host $fullName.ToUpper()

# Convert to lowercase
Write-Host $fullName.ToLower()

Output:

Arjun Sharma
12
ARJUN SHARMA
arjun sharma

Integer Data Type

Integers hold whole numbers. They do not have a decimal point.

[int]$apples  = 10
[int]$oranges = 4

$total = $apples + $oranges
$diff  = $apples - $oranges
$mult  = $apples * $oranges
$div   = $apples / $oranges

Write-Host "Total:    $total"
Write-Host "Diff:     $diff"
Write-Host "Multiply: $mult"
Write-Host "Divide:   $div"

Output:

Total:    14
Diff:     6
Multiply: 40
Divide:   2.5

Double and Decimal Data Types

[double]$pi       = 3.14159265
[decimal]$invoice = 1499.99

Write-Host "Pi value: $pi"
Write-Host "Invoice amount: $invoice"

# Decimal is more precise – use for money calculations
[decimal]$tax   = 0.18
[decimal]$total = $invoice + ($invoice * $tax)
Write-Host "Total with tax: $total"

Output:

Pi value: 3.14159265
Invoice amount: 1499.99
Total with tax: 1769.9882

Boolean Data Type

A boolean holds only two values: $true or $false. Booleans control decision-making in scripts.

[bool]$isLoggedIn = $true
[bool]$hasError   = $false

Write-Host "User logged in: $isLoggedIn"
Write-Host "Error present: $hasError"

# Use in an if statement
if ($isLoggedIn) {
    Write-Host "Access granted"
}

Output:

User logged in: True
Error present: False
Access granted

DateTime Data Type

[datetime]$today     = Get-Date
[datetime]$birthday  = "1995-08-15"

Write-Host "Today: $today"
Write-Host "Birthday: $birthday"

# Calculate age
$age = ($today - $birthday).Days / 365
Write-Host "Age in years: $([math]::Round($age, 1))"

Output:

Today: 03/21/2026 10:30:00
Birthday: 08/15/1995 00:00:00
Age in years: 30.6

Type Conversion

PowerShell can convert one data type into another. This is called type casting.

Implicit Conversion (Automatic)

$num    = 10
$result = $num + 5.5   # int + double → PowerShell returns double automatically
Write-Host $result     # Output: 15.5

Explicit Conversion (Manual)

# Convert string to integer
$strNum  = "100"
$intNum  = [int]$strNum
Write-Host ($intNum + 50)   # Output: 150

# Convert integer to string
$num     = 42
$strVal  = [string]$num
Write-Host ("Number is: " + $strVal)   # Output: Number is: 42

# Convert string to boolean
[bool]"true"   # Returns True
[bool]"false"  # Returns True (non-empty string is always True!)
[bool]""       # Returns False (empty string is False)

# Convert string to DateTime
[datetime]"2026-01-01"

Checking Data Type

$value = 3.14

# Method 1 – GetType()
$value.GetType().Name          # Output: Double

# Method 2 – is operator
$value -is [double]            # Output: True
$value -is [string]            # Output: False

# Method 3 – GetType().FullName
$value.GetType().FullName      # Output: System.Double

Type Mismatch Example

# What happens when types do not match
$a = "10"   # String
$b = 5      # Integer

Write-Host ($a + $b)    # Output: 105 (string concatenation, not addition!)
Write-Host ([int]$a + $b)   # Output: 15 (correct – cast string to int first)

This example shows why type awareness matters. Adding a string "10" to an integer 5 returns "105" (string concat), not 15. Explicitly converting $a to [int] fixes the result.

Null Values

$emptyValue = $null

# Check if a variable is null
if ($emptyValue -eq $null) {
    Write-Host "Variable has no value"
}

# Assign a default if null
$name = $null
$displayName = if ($name) { $name } else { "Guest" }
Write-Host "Hello, $displayName"

Output:

Variable has no value
Hello, Guest

Summary

PowerShell supports all standard data types through the .NET type system. Strings store text, integers and doubles hold numbers, booleans store true/false values, and DateTime handles date operations. PowerShell detects types automatically but explicit type declarations prevent hard-to-find bugs, especially in calculations involving mixed types. Always use [decimal] for financial values and [datetime] when working with dates and durations.