Match expression (PHP 8) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a match expression in PHP 8?

A match expression is a new control structure in PHP 8 that allows you to compare a value against multiple conditions and return a result. It is similar to switch but more concise and returns a value.

intermediate

How does match differ from switch in PHP?

Unlike switch, match is an expression that returns a value, supports strict type comparisons, does not allow fall-through, and requires all cases to be handled or a default to be provided.

intermediate

What happens if no case matches and no default is provided in a match expression?

If no case matches and there is no default case, a UnhandledMatchError exception is thrown at runtime.

beginner

Can a match expression have multiple conditions for a single case?

Yes, you can list multiple conditions separated by commas for a single case in a match expression, and if any condition matches, that case's value is returned.

beginner

Write a simple match expression that returns 'Weekend' for 6 or 7, and 'Weekday' for 1 to 5.

Example:

$dayType = match($day) {
  6, 7 => 'Weekend',
  1, 2, 3, 4, 5 => 'Weekday',
  default => 'Invalid day',
};

What type of comparison does match use in PHP 8?

A Loose comparison (==)

B Strict comparison (===)

C Bitwise comparison

D Reference comparison

match uses strict comparison (===), meaning types and values must match exactly.

What happens if a match expression has no matching case and no default?

A Returns false

B Returns null

C Executes the last case

D Throws an UnhandledMatchError exception

PHP throws an UnhandledMatchError exception if no case matches and no default is provided.

Which of these is NOT true about match expressions?

A They can return a value

B They require all cases to be handled or a default

C They allow fall-through between cases

D They use strict type comparison

match expressions do NOT allow fall-through; each case is exclusive.

How do you specify multiple conditions for one case in a match expression?

A Separate conditions with commas

B Use multiple <code>case</code> lines

C Use logical OR operators

D Use arrays

Multiple conditions for one case are separated by commas in match.

Which PHP version introduced the match expression?

A PHP 8.0

B PHP 7.3

C PHP 8.1

D PHP 7.4

match expressions were introduced in PHP 8.0.

Explain how a match expression works in PHP 8 and how it differs from a switch statement.

Think about how match is more like a value-returning expression than a statement.

Write a match expression that categorizes a number as 'small' for 1-3, 'medium' for 4-6, and 'large' for 7-9, with a default of 'unknown'.

Use commas to list multiple values for each case.

Practice

1. What is the main advantage of using a match expression in PHP 8 compared to a switch statement?

easy

A. It returns a value and uses strict comparison.

B. It allows fall-through between cases.

C. It only works with strings.

D. It requires a default case.

Solution

1. Step 1: Understand match vs switch behavior

   Match expressions return a value directly, unlike switch which is a statement.

2. Step 2: Identify comparison type

   Match uses strict comparison (===), while switch uses loose comparison (==).

3. Final Answer:

   It returns a value and uses strict comparison. -> Option A

4. Quick Check:

   Match returns value + strict check [OK]

Hint: Remember: match returns values and checks types strictly [OK]

Common Mistakes:

• Thinking match allows fall-through like switch
• Believing match works only with strings
• Assuming default case is mandatory in match

2. Which of the following is the correct syntax for a simple match expression in PHP 8?

easy

A. match ($value) { 1 => 'one', 2 => 'two', default => 'other' };

B. match $value { 1: 'one', 2: 'two', default: 'other' };

C. match ($value) { 1: 'one', 2: 'two', default => 'other' };

D. match ($value) { 1 => 'one', 2 => 'two', _ => 'other' };

Solution

1. Step 1: Recall match syntax

   Match uses parentheses around the expression and curly braces with arrows (=>) for cases.

2. Step 2: Identify correct default syntax

   Default case uses the keyword default with =>, not _ or colon.

3. Final Answer:

   match ($value) { 1 => 'one', 2 => 'two', default => 'other' }; -> Option A

4. Quick Check:

   Correct syntax uses parentheses, arrows, and default keyword [OK]

Hint: Use parentheses and arrows => with default keyword [OK]

Common Mistakes:

• Using colon : instead of arrow =>
• Omitting parentheses around the match expression
• Using _ instead of default for fallback

3. What will be the output of the following PHP code?

$status = 2;
$message = match($status) {
    1 => 'Pending',
    2 => 'Approved',
    3 => 'Rejected',
    default => 'Unknown'
};
echo $message;

medium

A. Pending

B. Unknown

C. Rejected

D. Approved

Solution

1. Step 1: Identify the value of $status

   $status is set to 2.

2. Step 2: Match $status to cases

   Case 2 matches 'Approved'.

3. Final Answer:

   Approved -> Option D

4. Quick Check:

   Value 2 matches 'Approved' [OK]

Hint: Match returns the value for exact case match [OK]

Common Mistakes:

• Confusing default case with matched case
• Assuming loose comparison might match wrong case
• Forgetting match returns a value, not prints it

4. Identify the error in this PHP 8 match expression code:

$input = 'banana';
$result = match($input) {
    'apple' => 'fruit',
    'carrot' => 'vegetable'
};
echo $result;

medium

A. Match expression cannot use strings as cases.

B. Syntax error due to missing semicolon after match.

C. Missing default case causes UnhandledMatchError.

D. Variable $result is not assigned properly.

Solution

1. Step 1: Check for default case presence

   The match expression lacks a default case for unmatched values.

2. Step 2: Understand consequences

   If input does not match any case, PHP throws UnhandledMatchError.

3. Final Answer:

   Missing default case causes UnhandledMatchError. -> Option C

4. Quick Check:

   Always include default to avoid errors [OK]

Hint: Always add default case to handle unmatched values [OK]

Common Mistakes:

• Assuming default case is optional
• Thinking strings can't be used as match cases
• Confusing syntax errors with runtime errors

5. You want to categorize a number into 'small', 'medium', or 'large' using a PHP 8 match expression. Which code correctly implements this logic for:
- small: 1 or 2
- medium: 3 or 4
- large: any other number

$num = 3;
// Your match expression here

hard

A. match($num) { 1, 2 => 'small', 3, 4 => 'medium', _ => 'large' };

B. match($num) { 1, 2 => 'small', 3, 4 => 'medium', default => 'large' };

C. match $num { 1, 2 => 'small', 3, 4 => 'medium', default => 'large' };

D. match($num) { 1, 2: 'small', 3, 4: 'medium', default => 'large' };

Solution

1. Step 1: Use comma-separated values for multiple cases

   PHP 8 match allows multiple values per case separated by commas.

2. Step 2: Use correct default keyword

   Default fallback must use default keyword, not underscore or other.

3. Final Answer:

   match($num) { 1, 2 => 'small', 3, 4 => 'medium', default => 'large' }; -> Option B

4. Quick Check:

   Multiple values + default keyword = match($num) { 1, 2 => 'small', 3, 4 => 'medium', default => 'large' }; [OK]

Hint: Use commas for multiple cases and default keyword for fallback [OK]

Common Mistakes:

• Using _ instead of default for fallback
• Not separating multiple cases with commas
• Confusing syntax with switch statement