Enum backed values in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of enum backed value access

What is the output of this PHP code using backed enums?

PHP

<?php
enum Status: string {
    case Pending = 'pending';
    case Active = 'active';
    case Archived = 'archived';
}

echo Status::Active->value;

A Status::Active

B Active

C pending

D active

💡 Hint

Access the string value of the enum case using ->value.

In PHP backed enums, each case has a value property that holds its backed value. Here, Status::Active has the string 'active'.

❓ Predict Output

intermediate

Enum from method with backed values

What will this code output?

PHP

<?php
enum Level: int {
    case Low = 1;
    case Medium = 5;
    case High = 10;
}

$level = Level::from(5);
echo $level->name;

A Level::Medium

B 5

C Medium

D Low

💡 Hint

The from() method returns the enum case matching the value.

Level::from(5) returns the enum case with value 5, which is Medium. Accessing ->name gives 'Medium'.

❓ Predict Output

advanced

What error does this enum code raise?

What error will this PHP code produce?

PHP

<?php
enum Color: string {
    case Red = 'red';
    case Green = 'green';
    case Blue = 'blue';
}

$color = Color::from('yellow');

A No error, returns null

B ValueError

C ParseError

D TypeError

💡 Hint

from() throws an error if the value is not defined in the enum.

The from() method throws a ValueError if the given value does not match any enum case.

🧠 Conceptual

advanced

Difference between from() and tryFrom() in backed enums

Which statement correctly describes the difference between from() and tryFrom() methods in PHP backed enums?

A from() throws an error if no matching value; tryFrom() returns null instead.

B from() returns null if no matching value; tryFrom() throws an error instead.

C Both methods throw errors if no matching value is found.

D Both methods return null if no matching value is found.

💡 Hint

One method is safer and returns null instead of error.

from() throws a ValueError if no matching case is found; tryFrom() returns null instead of throwing.

❓ Predict Output

expert

Output of enum backed values in array map

What is the output of this PHP code?

PHP

<?php
enum Priority: int {
    case Low = 1;
    case Medium = 5;
    case High = 10;
}

$values = array_map(fn($p) => $p->value, [Priority::Low, Priority::High]);
print_r($values);

A

Array
(
    [0] => 1
    [1] => 10
)

B

Array
(
    [0] => Low
    [1] => High
)

C

Array
(
    [0] => Priority::Low
    [1] => Priority::High
)

D

Array
(
    [0] => 0
    [1] => 1
)

💡 Hint

array_map extracts the ->value property from each enum case.

The code maps each enum case to its backed int value, resulting in [1, 10].