Switch with wildcard and regex in PowerShell - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to match the input using a wildcard pattern in the switch statement.

PowerShell

switch -Wildcard ($input) {
    [1] { Write-Output "Matched wildcard pattern" }
    default { Write-Output "No match" }
}

Drag options to blanks, or click blank then click option'

A"hello?"

B"^hello.*$"

C"hello*"

D"*world"

Attempts:

3 left

💡 Hint

Common Mistakes

Using regex pattern with -Wildcard instead of a wildcard pattern.

Forgetting to put the pattern in quotes.

The -Wildcard parameter expects a wildcard pattern like "hello*" to match strings starting with 'hello'.

2fill in blank

medium

Complete the code to match the input using a regex pattern in the switch statement.

PowerShell

switch -Regex ($input) {
    [1] { Write-Output "Matched regex pattern" }
    default { Write-Output "No match" }
}

Drag options to blanks, or click blank then click option'

A"^hello.*$"

B"hello*"

C"hello?"

D"*world"

Attempts:

3 left

💡 Hint

Common Mistakes

Using wildcard pattern with -Regex instead of a regex pattern.

Not anchoring the regex pattern properly.

The -Regex parameter expects a regex pattern like '^hello.*$' to match strings starting with 'hello'.

3fill in blank

hard

Fix the error in the switch statement to correctly match input ending with 'end' using wildcard.

PowerShell

switch -Wildcard ($input) {
    [1] { Write-Output "Ends with 'end'" }
    default { Write-Output "No match" }
}

Drag options to blanks, or click blank then click option'

A"end*"

B"*end"

C"?end"

D"*en"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'end*' which matches strings starting with 'end' instead of ending.

Using '?' which matches exactly one character.

The wildcard '*end' matches any string ending with 'end'.

4fill in blank

hard

Fill both blanks to match input starting with 'start' using regex and containing digits.

PowerShell

switch -Regex ($input) {
    [1] { Write-Output "Starts with start" }
    [2] { Write-Output "Contains digits" }
    default { Write-Output "No match" }
}

Drag options to blanks, or click blank then click option'

A"^start"

B"\d+"

C"start$"

D"[a-z]+"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'start$' which matches strings ending with 'start'.

Using '[a-z]+' which matches letters but not digits.

The pattern '^start' matches strings starting with 'start'. The pattern '\d+' matches strings containing one or more digits.

5fill in blank

hard

Fill all three blanks to create a switch that matches input exactly 'yes', matches input containing 'no' anywhere, and matches input starting with 'maybe' using regex.

PowerShell

switch -Regex ($input) {
    [1] { Write-Output "Exact yes" }
    [2] { Write-Output "Contains no" }
    [3] { Write-Output "Starts with maybe" }
    default { Write-Output "No match" }
}

Drag options to blanks, or click blank then click option'

A"^yes$"

B"no"

C"^maybe"

D"yes"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'yes' without anchors matches any string containing 'yes', not exactly 'yes'.

Using '^no' which matches strings starting with 'no' only.

The pattern '^yes$' matches exactly 'yes'. The pattern 'no' matches any string containing 'no'. The pattern '^maybe' matches strings starting with 'maybe'.

Practice

1. What does the -Wildcard parameter do in a PowerShell switch statement?

easy

A. It matches patterns using complex regular expressions.

B. It makes the switch statement run faster by skipping checks.

C. It forces the switch to ignore case sensitivity.

D. It matches patterns using simple wildcards like * and ?.

Solution

1. Step 1: Understand the role of -Wildcard

   The -Wildcard parameter allows pattern matching using simple wildcards such as * (any characters) and ? (single character).

2. Step 2: Differentiate from -Regex

   Unlike -Regex, which uses complex regular expressions, -Wildcard is simpler and easier for basic pattern matching.

3. Final Answer:

   It matches patterns using simple wildcards like * and ?. -> Option D

4. Quick Check:

   -Wildcard = simple wildcard matching [OK]

Hint: Remember: Wildcard = * and ? patterns, Regex = complex patterns [OK]

Common Mistakes:

• Confusing -Wildcard with -Regex
• Thinking -Wildcard ignores case by default
• Assuming -Wildcard speeds up execution

2. Which of the following is the correct syntax to use a switch statement with wildcard matching in PowerShell?

easy

A. switch ($input) { '*test*' -Wildcard { 'Match' } }

B. switch ($input) -Wildcard { '*test*' { 'Match' } }

C. switch -Wildcard ($input) { '*test*' { 'Match' } }

D. switch ($input) { -Wildcard '*test*' { 'Match' } }

Solution

1. Step 1: Identify correct parameter placement

   In PowerShell, the -Wildcard parameter is placed immediately after switch and before the input expression.

2. Step 2: Check the pattern and block syntax

   The pattern '*test*' and the script block '{ 'Match' }' are correctly placed inside the switch braces.

3. Final Answer:

   switch -Wildcard ($input) { '*test*' { 'Match' } } -> Option C

4. Quick Check:

   Parameter right after switch keyword = switch -Wildcard ($input) { '*test*' { 'Match' } } [OK]

Hint: Put -Wildcard right after switch, before input [OK]

Common Mistakes:

• Placing -Wildcard inside the switch block
• Putting -Wildcard after the input variable
• Using -Wildcard as a pattern inside braces

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

switch -Regex ('apple', 'banana', 'cherry') {
  '^a' { 'Starts with a' }
  'an' { 'Contains an' }
  default { 'No match' }
}

medium

A. Starts with a
Contains an
No match

B. Starts with a
No match
No match

C. No match
Contains an
No match

D. Starts with a
Contains an
Contains an

Solution

1. Step 1: Check each input against regex patterns

   'apple' matches '^a' (starts with 'a'), so outputs 'Starts with a'. 'banana' contains 'an', so matches 'an' pattern, outputs 'Contains an'. 'cherry' matches none, so outputs 'No match'.

2. Step 2: Confirm output order

   The outputs correspond to each input in order: 'apple' -> 'Starts with a', 'banana' -> 'Contains an', 'cherry' -> 'No match'.

3. Final Answer:

   Starts with a Contains an No match -> Option A

4. Quick Check:

   Regex matches each input correctly = Starts with a Contains an No match [OK]

Hint: Match each input line by line with regex patterns [OK]

Common Mistakes:

• Assuming only first match per input
• Confusing regex anchors like ^
• Ignoring default case output

4. Identify the error in this PowerShell switch statement using wildcard matching:

switch ($word) -Wildcard {
  'he*' { 'Starts with he' }
  '*lo' { 'Ends with lo' }
  default { 'No match' }
}

medium

A. The -Wildcard parameter should be before the input variable.

B. The patterns 'he*' and '*lo' are invalid wildcards.

C. The default case is missing a script block.

D. The switch statement cannot use wildcards with variables.

Solution

1. Step 1: Check parameter placement

   The -Wildcard parameter must come immediately after the switch keyword, not after the input variable.

2. Step 2: Validate patterns and default block

   The patterns 'he*' and '*lo' are valid wildcards. The default case has a proper script block. Using wildcards with variables is allowed.

3. Final Answer:

   The -Wildcard parameter should be before the input variable. -> Option A

4. Quick Check:

   Parameter placement error = The -Wildcard parameter should be before the input variable. [OK]

Hint: Place -Wildcard right after switch, before input variable [OK]

Common Mistakes:

• Putting -Wildcard after input variable
• Thinking wildcards are invalid patterns
• Omitting script block braces

5. You want to categorize a list of filenames using switch with both wildcard and regex patterns. Which approach correctly combines -Wildcard and -Regex in one script to handle different patterns?

hard

A. Use a single switch with both -Wildcard and -Regex parameters together.

B. Use two separate switch statements: one with -Wildcard, one with -Regex, processing the list twice.

C. Use -Wildcard and -Regex as pattern modifiers inside one switch statement.

D. Use -Regex only and convert wildcards to regex patterns manually.

Solution

1. Step 1: Understand parameter exclusivity

   PowerShell's switch does not support using -Wildcard and -Regex together in one statement. They are mutually exclusive parameters.

2. Step 2: Choose practical approach

   To handle both wildcard and regex patterns, use two separate switch statements: one with -Wildcard and one with -Regex, processing the list twice.

3. Final Answer:

   Use two separate switch statements: one with -Wildcard, one with -Regex, processing the list twice. -> Option B

4. Quick Check:

   Separate switches for wildcard and regex = Use two separate switch statements: one with -Wildcard, one with -Regex, processing the list twice. [OK]

Hint: Use separate switches for wildcard and regex patterns [OK]

Common Mistakes:

• Trying to combine -Wildcard and -Regex in one switch
• Assuming pattern modifiers inside switch block
• Converting wildcards manually instead of separate switches