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Strings, Arrays, and Hashtables

These three data structures form the backbone of everyday PowerShell scripting.

Strings: Single vs Double Quotes

Double quotes expand variables and escape sequences. Single quotes treat everything as literal text:

powershell

$name = "Alice"
"Hello, $name!"    # Hello, Alice!
'Hello, $name!'    # Hello, $name!

Use $() inside double quotes to evaluate expressions:

powershell

"There are $($items.Count) items."

Key Concept: Use single quotes when you want the exact literal string. Use double quotes when you need variable expansion or special characters like ` n `` (newline).

String Methods

Strings in PowerShell are .NET objects, so they have built-in methods:

powershell

"hello world".ToUpper()              # HELLO WORLD
"hello world".Replace("world", "PS") # hello PS
"one,two,three".Split(",")           # array: one two three
"  spaces  ".Trim()                  # spaces

Arrays

Create arrays with @() or comma-separated values. Access elements by zero-based index:

powershell

$colors = @("red", "green", "blue")
$colors[0]     # red
$colors[-1]    # blue (last element)
$colors += "yellow"   # adds to the array
$colors.Count  # 4

Use the range operator to create number sequences:

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$nums = 1..5   # array: 1, 2, 3, 4, 5

Key Concept: The += operator creates a new array behind the scenes. For small arrays this is fine, but for large-scale operations, use a [System.Collections.Generic.List[object]] instead.

Hashtables

A hashtable stores key-value pairs using @{}:

powershell

$person = @{
    Name = "Alice"
    Age  = 30
    City = "Seattle"
}
$person["Name"]   # Alice
$person.Age       # 30
$person["Role"] = "Admin"   # add a new key

Ordered Hashtables

Regular hashtables do not guarantee key order. Use [ordered] when order matters:

powershell

$config = [ordered]@{
    Host = "localhost"
    Port = 8080
    SSL  = $true
}

This preserves the order you defined the keys in, which is important for display and CSV export.

Exercises

0/5 completed

Given $city = "Seattle", write a double-quoted string that produces: "I live in Seattle." using variable expansion (not concatenation).

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