Enums in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a basic enum named Color.

PHP

<?php
enum [1] {
    case RED;
    case GREEN;
    case BLUE;
}

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

AColor

BColors

CCOLOR

Dcolor

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase enum name like 'color' which is not conventional.

Using plural form 'Colors' which is not required.

The enum name should be Color with uppercase first letter as per convention.

2fill in blank

medium

Complete the code to access the GREEN case of the Color enum.

PHP

<?php
$green = Color::[1];

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AGreen

BgreenCase

Cgreen

DGREEN

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or camelCase which will cause errors.

Using plural or modified case names.

Enum cases are accessed using uppercase names exactly as declared, so GREEN is correct.

3fill in blank

hard

Fix the error in the enum declaration by completing the missing keyword.

PHP

<?php
[1] Color {
    case RED;
    case BLUE;
}

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

Aclass

Binterface

Cenum

Dtrait

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'class' or 'interface' instead of 'enum'.

Forgetting the keyword entirely.

The keyword to declare an enum in PHP is enum.

4fill in blank

hard

Fill both blanks to create a backed enum with string values.

PHP

<?php
enum Status: [1] {
    case ACTIVE = [2];
    case INACTIVE = 'inactive';
}

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Astring

B'active'

Cint

D'active_status'

Attempts:

3 left

💡 Hint

Common Mistakes

Using int type but assigning string values.

Not quoting string values.

Backed enums require specifying the type like string and assigning string values like 'active'.

5fill in blank

hard

Fill all three blanks to iterate over enum cases and print their names.

PHP

<?php
foreach (Status::[1]() as [2]) {
    echo [3]->name . PHP_EOL;
}

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Acases

Bcase

C$status

D$case

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong method name like 'case()' instead of 'cases()'.

Using variable names without $ sign.

Trying to access name as a method instead of property.

Use cases() to get all enum cases, iterate with a variable like $case, and access the name property.

Practice

1. What is the main purpose of using enum in PHP?

easy

A. To group related constant values under one name

B. To create a new type of variable that can hold any value

C. To define functions inside classes

D. To declare variables with dynamic types

Solution

1. Step 1: Understand what enums represent

   Enums are used to group related constant values, like fixed options or states.

2. Step 2: Compare with other options

   Other options describe unrelated concepts: variables or functions, not enums.

3. Final Answer:

   To group related constant values under one name -> Option A

4. Quick Check:

   Enums = group constants [OK]

Hint: Enums group fixed options clearly [OK]

Common Mistakes:

• Thinking enums create dynamic variables
• Confusing enums with classes or functions
• Assuming enums can hold any value

2. Which of the following is the correct syntax to declare a backed enum with string values in PHP?

easy

A. enum Status: string { case Active = 'active'; case Inactive = 'inactive'; }

B. enum Status { case Active = 'active'; case Inactive = 'inactive'; }

C. enum Status: int { case Active = 'active'; case Inactive = 'inactive'; }

D. enum Status: string { Active = 'active'; Inactive = 'inactive'; }

Solution

1. Step 1: Identify backed enum syntax

   Backed enums require a type after the enum name, like : string, and cases with assigned values.

2. Step 2: Check each option

   enum Status: string { case Active = 'active'; case Inactive = 'inactive'; } correctly uses enum Status: string { case Active = 'active'; ... }. enum Status { case Active = 'active'; case Inactive = 'inactive'; } misses the type. enum Status: int { case Active = 'active'; case Inactive = 'inactive'; } uses wrong type int with string values. enum Status: string { Active = 'active'; Inactive = 'inactive'; } misses case keyword.

3. Final Answer:

   enum Status: string { case Active = 'active'; case Inactive = 'inactive'; } -> Option A

4. Quick Check:

   Backed enum syntax = enum Status: string { case Active = 'active'; case Inactive = 'inactive'; } [OK]

Hint: Backed enums need type and 'case' keyword [OK]

Common Mistakes:

• Omitting the enum type after colon
• Forgetting 'case' before each value
• Assigning string values to int enums

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

enum Direction { case North; case South; case East; case West; }
$dir = Direction::East;
echo $dir->name;

medium

A. Error: Cannot access name

B. direction::East

C. East case

D. East

Solution

1. Step 1: Understand enum case name property

   In PHP enums, $dir->name returns the case name as a string.

2. Step 2: Check the assigned case

   The variable $dir is assigned Direction::East, so $dir->name is "East".

3. Final Answer:

   East -> Option D

4. Quick Check:

   Enum case name = East [OK]

Hint: Use ->name to get enum case name string [OK]

Common Mistakes:

• Expecting the value instead of name
• Trying to print enum case directly
• Confusing case name with enum class name

4. Identify the error in this PHP enum declaration:

enum Color {
  case Red = 1;
  case Green = 2;
  case Blue;
}

medium

A. Case Blue should have a value assigned

B. Missing enum type for backed enum values

C. Enum name must be lowercase

D. Cases cannot have integer values

Solution

1. Step 1: Check enum type for backed values

   When enum cases have assigned values (like 1, 2), the enum must declare a type (e.g., : int).

2. Step 2: Analyze the given enum

   The enum Color assigns values to some cases but does not specify : int after the enum name, causing a syntax error.

3. Final Answer:

   Missing enum type for backed enum values -> Option B

4. Quick Check:

   Backed enums need type declared [OK]

Hint: Backed enums must declare type after enum name [OK]

Common Mistakes:

• Not declaring enum type when assigning values
• Assuming cases can mix assigned and unassigned values
• Thinking enum names must be lowercase

5. Given this enum:

enum Status: string {
  case Pending = 'pending';
  case Approved = 'approved';
  case Rejected = 'rejected';
}

Which code correctly converts a string $input to the matching Status enum case or returns null if no match?

hard

A. new Status($input)

B. Status::from($input)

C. Status::tryFrom($input)

D. Status::$input

Solution

1. Step 1: Understand enum methods for backed enums

   PHP backed enums provide from() which throws error if no match, and tryFrom() which returns null if no match.

2. Step 2: Match requirement

   The question asks to return matching enum or null if no match, so tryFrom() is correct.

3. Final Answer:

   Status::tryFrom($input) -> Option C

4. Quick Check:

   Safe enum conversion = tryFrom() [OK]

Hint: Use tryFrom() to safely convert string to enum [OK]

Common Mistakes:

• Using from() which throws error on no match
• Trying to instantiate enum with new
• Accessing enum cases as static properties