Conditionals

PowerShell · Reference cheat sheet

📋 Overview

Branch with if / elseif / else, switch, and ternary (? : in PowerShell 7+). Comparison operators are letter-based (-eq, -lt, …) and case-insensitive by default for strings. Use -match for regex and -in / -contains for membership.

🔧 Core concepts

Null-conditional: $x?.Prop. Null-coalescing: $x ?? 'default' (PS 7+).

💡 Examples

If / elseif:

if ($null -eq $path) {
  throw 'path required'
} elseif (Test-Path $path -PathType Leaf) {
  'file'
} else {
  'missing or directory'
}

Switch:

switch -Regex ($name) {
  '^ERROR'   { 'err'; break }
  '^WARN'    { 'warn'; break }
  default    { 'info' }
}

Ternary and null coalesce (PS 7+):

$mode = $IsWindows ? 'win' : 'unix'
$port = $env:PORT ?? '8080'

Membership:

if ($ext -in @('.jpg', '.png')) { 'image' }
if (@(1,2,3) -contains 2) { 'yes' }

⚠️ Pitfalls

• Put $null on the left: $null -eq $x avoids array comparison surprises.
• -contains is for collections on the left; -in reads more naturally for scalars.
• String compares are case-insensitive unless you use -ceq / -clike / -cmatch.
• if (@()) is false; if @(0) is true (non-empty array)—don’t confuse with truthiness of elements.
• Assignment inside conditions is uncommon; = is not comparison—use -eq.
• switch falls through without break in some modes—be explicit.

🔗 Related

• variables.md
• loops.md
• error_handling.md
• pipeline.md
• vs_bash.md