The switch Statement

switch compares a value against several options. PowerShell's switch is unusually powerful: it supports wildcards, regular expressions, script blocks, and even whole arrays and files.

$day = 'Saturday'
switch ($day) {
  'Saturday' { 'Weekend!' }
  'Sunday'   { 'Weekend!' }
  'Friday'   { 'Almost weekend' }
  default    { 'Weekday' }
}

Weekend!

Wildcards, regex, and conditions

foreach ($file in 'photo.JPG', 'report.pdf', 'notes.txt', 'archive.tar.gz') {
  $type = switch -Wildcard ($file) {
    '*.jpg'    { 'image'; break }
    '*.pdf'    { 'document'; break }
    '*.tar.gz' { 'archive'; break }
    default    { 'other' }
  }
  "${file}: $type"
}

$score = 84
switch ($score) {
  { $_ -ge 90 } { 'A'; break }
  { $_ -ge 80 } { 'B'; break }
  default       { 'F' }
}

photo.JPG: image
report.pdf: document
notes.txt: other
archive.tar.gz: archive
B

• -Wildcard matches patterns (case-insensitive by default); -Regex matches regular expressions.
• A script block as the condition ({ $_ -ge 90 }) allows any test.
• Unlike most languages, PowerShell checks every case, so several can match. break stops after the first match.
• "${file}:" uses braces so the colon isn't read as part of the variable name.

Switching over a collection

Given an array, switch runs once per element:

switch (1, 2, 3, 4, 5) {
  { $_ % 2 -eq 0 } { "$_ is even" }
}

2 is even
4 is even

switch -File log.txt { ... } does the same for each line of a file.

Common mistakes

• Forgetting break when conditions overlap, so a value produces several outputs.