String comparison (-like, -match) in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PowerShell command?

Consider the following command:

$result = 'HelloWorld' -like 'Hello*'

What is the value of $result?

PowerShell

$result = 'HelloWorld' -like 'Hello*'
Write-Output $result

A True

B False

C HelloWorld

D Error

💡 Hint

The -like operator uses wildcard matching with * as any characters.

The string 'HelloWorld' matches the pattern 'Hello*' because it starts with 'Hello' followed by any characters, so the result is True.

💻 Command Output

intermediate

What does this PowerShell command output?

Given the command:

$result = 'PowerShell123' -match '\d{3}'

What is the value of $result?

PowerShell

$result = 'PowerShell123' -match '\d{3}'
Write-Output $result

A False

B 123

C True

D Error

💡 Hint

The -match operator returns True if the regex pattern matches anywhere in the string.

The pattern '\d{3}' looks for three digits in a row. 'PowerShell123' ends with '123', so the match is found and the result is True.

📝 Syntax

advanced

Which option correctly uses -like to check if a string ends with '.txt'?

You want to check if the variable $fileName ends with '.txt' using the -like operator. Which of these is correct?

A $fileName -like 'txt*.'

B $fileName -like '.txt*'

C $fileName -like '*txt.'

D $fileName -like '*.txt'

💡 Hint

The * wildcard matches any characters before '.txt' at the end.

To check if a string ends with '.txt', the pattern should be '*.txt' where * matches any characters before '.txt'.

💻 Command Output

advanced

What is the output of this PowerShell snippet?

Analyze the code:

$text = 'Data123'
if ($text -match '^Data\d+$') { 'Match' } else { 'No Match' }

What will it output?

PowerShell

$text = 'Data123'
if ($text -match '^Data\d+$') { 'Match' } else { 'No Match' }

A No Match

B Match

C Error

D Data123

💡 Hint

The regex ^Data\d+$ means string starts with 'Data' followed by one or more digits till end.

The string 'Data123' matches the pattern because it starts with 'Data' and ends with digits only, so output is 'Match'.

🧠 Conceptual

expert

Which statement about -like and -match is TRUE in PowerShell?

Choose the correct statement about the difference between -like and -match operators.

A -like uses wildcard patterns and is case-insensitive by default; -match uses regular expressions and is case-insensitive by default.

B -like uses regular expressions and is case-sensitive; -match uses wildcard patterns and is case-insensitive.

C -like and -match both use regular expressions but differ in case sensitivity.

D -like uses wildcard patterns and is case-sensitive; -match uses regular expressions and is case-sensitive.

💡 Hint

Think about pattern types and default case sensitivity.

-like uses simple wildcard patterns (*, ?) and is case-insensitive by default. -match uses full regular expressions and is also case-insensitive by default.

Practice

1. Which operator in PowerShell uses simple wildcard patterns for string comparison?

easy

A. -contains

B. -like

C. -match

D. -eq

Solution

1. Step 1: Understand the purpose of -like

   The -like operator uses simple wildcard characters like * and ? to match patterns in strings.

2. Step 2: Compare with -match

   The -match operator uses regular expressions, which are more complex than simple wildcards.

3. Final Answer:

   -like -> Option B

4. Quick Check:

   Simple wildcard matching = -like [OK]

Hint: Remember: -like = wildcards, -match = regex [OK]

Common Mistakes:

• Confusing -like with -match
• Thinking -contains works like -like
• Assuming -eq supports wildcards

2. Which of the following is the correct syntax to check if the variable $name contains the substring 'John' using -like?

easy

A. $name -like 'John*'

B. $name -like 'John?'

C. $name -like '*John*'

D. $name -like '?John?'

Solution

1. Step 1: Understand wildcard usage with -like

   The asterisk (*) wildcard matches zero or more characters. To check if 'John' appears anywhere, use '*John*'.

2. Step 2: Analyze each option

   $name -like 'John*' checks if string starts with 'John'. $name -like '*John*' checks if 'John' is anywhere. $name -like '?John?' uses '?' which matches exactly one character, so it won't match 'John' alone. $name -like 'John?' checks if string starts with 'John' and has one more character.

3. Final Answer:

   $name -like '*John*' -> Option C

4. Quick Check:

   Substring anywhere = '*John*' [OK]

Hint: Use * before and after substring to match anywhere [OK]

Common Mistakes:

• Forgetting to use * wildcards around substring
• Using ? instead of * for multiple characters
• Assuming -like matches exact substring without wildcards

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

$text = 'PowerShell123'
if ($text -match '\d{3}$') { 'Ends with 3 digits' } else { 'No match' }

medium

A. Ends with 3 digits

B. No match

C. Syntax error

D. Empty output

Solution

1. Step 1: Understand the regex pattern '\d{3}$'

   This pattern matches exactly three digits (\d{3}) at the end of the string ($).

2. Step 2: Check the string 'PowerShell123'

   The string ends with '123', which is three digits, so the pattern matches.

3. Final Answer:

   Ends with 3 digits -> Option A

4. Quick Check:

   Regex matches end digits = 'Ends with 3 digits' [OK]

Hint: Use -match with regex to find patterns like digits [OK]

Common Mistakes:

• Confusing -like with regex patterns
• Not escaping backslash in regex
• Assuming -match returns boolean instead of string output

4. Identify the error in this PowerShell snippet:

$file = 'report.doc'
if ($file -clike '*.DOC') { 'Match found' } else { 'No match' }

medium

A. -clike is case-sensitive, so '*.DOC' won't match 'report.doc'

B. Wildcard * is missing

C. Quotes around pattern are incorrect

D. Variable $file is not defined

Solution

1. Step 1: Understand the -clike operator

   -clike is the case-sensitive counterpart to -like. It requires exact case matching for the pattern.

2. Step 2: Analyze the mismatch

   The string 'report.doc' ends with lowercase '.doc', but the pattern '*.DOC' specifies uppercase '.DOC'. Other options are invalid: * is present, quotes are correct, $file is defined.

3. Final Answer:

   -clike is case-sensitive, so '*.DOC' won't match 'report.doc' -> Option A

4. Quick Check:

   Case mismatch with -clike = no match [OK]

Hint: Remember: -clike = case-sensitive, -like = case-insensitive [OK]

Common Mistakes:

• Forgetting -clike is case-sensitive
• Thinking wildcards are missing
• Misunderstanding variable initialization

5. You want to filter a list of filenames to include only those that start with 'log' and end with a 4-digit year using PowerShell. Which command correctly uses -match to do this?

$files = @('log2020.txt', 'log2019.csv', 'data2020.log', 'log20a0.txt')

hard

A. $files | Where-Object { $_ -like 'log????' }

B. $files | Where-Object { $_ -like 'log*2020' }

C. $files | Where-Object { $_ -match 'log\d{4}$' }

D. $files | Where-Object { $_ -match '^log\d{4}' }

Solution

1. Step 1: Understand the pattern requirements

   We want filenames starting with 'log' (^log) followed immediately by exactly 4 digits (\d{4}).

2. Step 2: Analyze each option

   $files | Where-Object { $_ -match '^log\d{4}' } uses regex '^log\d{4}' which matches strings starting with 'log' plus 4 digits. $files | Where-Object { $_ -like 'log????' } uses -like with 'log????' which matches 'log' plus any 4 characters but not necessarily digits. $files | Where-Object { $_ -match 'log\d{4}$' } matches 'log' followed by 4 digits at the end, but the year is not necessarily at the end of the filename. $files | Where-Object { $_ -like 'log*2020' } matches 'log' followed by anything and ending with '2020', which is too specific.

3. Final Answer:

   $files | Where-Object { $_ -match '^log\d{4}' } -> Option D

4. Quick Check:

   Start with 'log' + 4 digits = $files | Where-Object { $_ -match '^log\d{4}' } [OK]

Hint: Use ^ for start and \d{4} for 4 digits in regex [OK]

Common Mistakes:

• Using -like with ? instead of digits
• Matching digits at end instead of start
• Confusing -like and -match patterns