Switch statement in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a switch statement in PowerShell?

A switch statement lets you test a value against multiple conditions. It runs the code block for the first matching case. It's like choosing a path based on different options.

beginner

How do you write a basic switch statement in PowerShell?

Use the keyword switch followed by parentheses with the value to check. Inside curly braces, list cases with their code blocks. Example:

switch ($value) {
  'a' { Write-Output 'Got a' }
  'b' { Write-Output 'Got b' }
}

beginner

What happens if no case matches in a PowerShell switch statement?

If no case matches, the switch statement does nothing and moves on. You can add a default case to handle unmatched values.

intermediate

Can a PowerShell switch statement handle multiple matches?

Yes! PowerShell switch can process multiple matches if you use the -Regex or -File options. By default, it stops after the first match.

beginner

How do you add a default case in a PowerShell switch statement?

Use the keyword default inside the switch block. It runs if no other case matches. Example:

switch ($value) {
  'a' { Write-Output 'Got a' }
  default { Write-Output 'No match found' }
}

What keyword starts a switch statement in PowerShell?

A switch

B case

C select

D if

The keyword switch starts the switch statement in PowerShell.

What happens if no case matches and there is no default in a PowerShell switch?

A It throws an error

B It runs the last case

C It repeats the switch

D It does nothing and continues

If no case matches and no default is given, the switch does nothing and continues.

How do you write a default case in a PowerShell switch?

A else { }

B default { }

C case default { }

D otherwise { }

Use default { } inside the switch block for unmatched cases.

Which option allows a PowerShell switch to match multiple cases?

A -All

B -Multiple

C -Regex

D -MatchAll

The -Regex option lets switch match multiple cases using patterns.

What is the correct syntax to check a variable $color for 'red' or 'blue' using switch?

A switch ($color) { 'red' { } 'blue' { } }

B switch $color { 'red' { } 'blue' { } }

C switch ($color) then { 'red' { } 'blue' { } }

D switch { $color == 'red' { } $color == 'blue' { } }

The correct syntax is switch ($color) { 'red' { } 'blue' { } }.

Explain how a switch statement works in PowerShell and when you might use it.

Think about choosing actions based on different options.

Write a simple PowerShell switch statement that prints 'Yes' if input is 'y', 'No' if 'n', and 'Unknown' otherwise.

Use default to catch all other inputs.

Practice

1. What is the main purpose of a switch statement in PowerShell?

easy

A. To create a variable

B. To repeat a block of code multiple times

C. To define a function

D. To choose one action from many based on a value

Solution

1. Step 1: Understand the role of switch

   A switch statement checks a value and picks the matching case to run.

2. Step 2: Compare with other options

   Loops repeat code, functions define reusable code, variables store data. Only switch picks actions based on value.

3. Final Answer:

   To choose one action from many based on a value -> Option D

4. Quick Check:

   Switch selects action by value = A [OK]

Hint: Switch picks code by matching value, like a menu choice [OK]

Common Mistakes:

• Confusing switch with loops
• Thinking switch defines variables
• Mixing switch with function definition

2. Which of the following is the correct syntax to start a switch statement in PowerShell?

easy

A. switch ($variable) { ... }

B. switch $variable { ... }

C. switch { $variable } ...

D. switch ($variable) then { ... }

Solution

1. Step 1: Recall switch syntax

   PowerShell requires parentheses around the value: switch ($variable) { ... }

2. Step 2: Check other options

   switch $variable { ... } misses parentheses, C has wrong braces, D uses invalid 'then'.

3. Final Answer:

   switch ($variable) { ... } -> Option A

4. Quick Check:

   Parentheses around variable = B [OK]

Hint: Always put the variable inside parentheses after switch [OK]

Common Mistakes:

• Omitting parentheses around the variable
• Using 'then' keyword incorrectly
• Wrong brace placement

3. What will be the output of this PowerShell code?

switch (3) {
  1 { 'One' }
  2 { 'Two' }
  3 { 'Three' }
  default { 'Other' }
}

medium

A. Three

B. Two

C. Other

D. One

Solution

1. Step 1: Identify the switch value

   The switch is checking the value 3.

2. Step 2: Match the case

   Case 3 matches and outputs 'Three'. Default is ignored because a match was found.

3. Final Answer:

   Three -> Option A

4. Quick Check:

   Value 3 matches case 3 = D [OK]

Hint: Match value to case; default runs only if no match [OK]

Common Mistakes:

• Choosing default even when a case matches
• Confusing case numbers
• Ignoring case order

4. Identify the error in this PowerShell switch statement:

switch $color {
  'red' { 'Stop' }
  'green' { 'Go' }
  default { 'Wait' }
}

medium

A. Missing quotes around case values

B. Missing parentheses around $color

C. Missing default case

D. Incorrect use of curly braces

Solution

1. Step 1: Check switch syntax

   PowerShell requires parentheses around the variable in switch: switch ($color) { ... }

2. Step 2: Verify other parts

   Quotes around case values and default case are correct; curly braces are used properly.

3. Final Answer:

   Missing parentheses around $color -> Option B

4. Quick Check:

   Parentheses required around variable = A [OK]

Hint: Always wrap the switch variable in parentheses [OK]

Common Mistakes:

• Omitting parentheses around the switch variable
• Thinking quotes are optional for strings
• Confusing default case necessity

5. You want to write a switch statement that prints 'Weekend' for Saturday and Sunday, 'Weekday' for Monday to Friday, and 'Invalid' for any other input. Which code snippet correctly implements this?

hard

A. switch ($day) { 'Saturday' { 'Weekend' } 'Sunday' { 'Weekend' } 'Monday','Tuesday','Wednesday','Thursday','Friday' { 'Weekday' } default { 'Invalid' } }

B. switch ($day) { 'Saturday' -or 'Sunday' { 'Weekend' } 'Monday' -or 'Tuesday' -or 'Wednesday' -or 'Thursday' -or 'Friday' { 'Weekday' } default { 'Invalid' } }

C. switch ($day) { 'Saturday' { 'Weekend' } 'Sunday' { 'Weekend' } 'Monday' { 'Weekday' } 'Tuesday' { 'Weekday' } 'Wednesday' { 'Weekday' } 'Thursday' { 'Weekday' } 'Friday' { 'Weekday' } default { 'Invalid' } }

D. switch ($day) { 'Saturday','Sunday' { 'Weekend' } 'Monday','Tuesday','Wednesday','Thursday','Friday' { 'Weekday' } default { 'Invalid' } }

Solution

1. Step 1: Recall PowerShell switch case syntax

   Each case must have exactly one pattern followed by { action }. Multiple values require separate case statements.

2. Step 2: Check each option

   A lists a separate case for each day: correct syntax and produces expected output.
   B uses -or which evaluates to $true (boolean) and won't match string days.
   C and D use commas to attempt grouping, but this causes syntax errors (unexpected token ',').

3. Final Answer:

   switch ($day) { 'Saturday' { 'Weekend' } 'Sunday' { 'Weekend' } 'Monday' { 'Weekday' } 'Tuesday' { 'Weekday' } 'Wednesday' { 'Weekday' } 'Thursday' { 'Weekday' } 'Friday' { 'Weekday' } default { 'Invalid' } } -> Option C

4. Quick Check:

   Separate cases per value, no commas in patterns = A [OK]

Hint: Use separate case statements for multiple matching values [OK]

Common Mistakes:

• Using '-or' inside switch case labels
• Trying to group values with commas (syntax error)
• Incorrectly assuming comma grouping works like other languages