Enums in PHP - Step-by-Step Execution

Concept Flow - Enums in PHP

Define enum with cases

↓

Use enum value in code

↓

Compare or switch on enum

↓

Get enum name or value

↓

End

This flow shows how you define an enum, use its values, compare or switch on them, and access their names or values.

Execution Sample

PHP

<?php
enum Status {
  case Pending;
  case Approved;
  case Rejected;
}

$current = Status::Approved;
if ($current === Status::Approved) {
  echo "Approved!";
}
?>

Defines an enum Status with three cases, sets current status to Approved, then checks and prints if it is Approved.

Execution Table

Step	Action	Evaluation	Result
1	Define enum Status with cases Pending, Approved, Rejected	N/A	Enum Status created
2	Assign $current = Status::Approved	N/A	$current holds Status::Approved
3	Check if $current === Status::Approved	$current === Status::Approved	True
4	Execute echo "Approved!"	Print output	Approved!
5	End of script	N/A	Script ends

💡 Script ends after printing 'Approved!' because condition is true and no more code.

Variable Tracker

Variable	Start	After Step 2	After Step 5
$current	undefined	Status::Approved	Status::Approved

Key Moments - 3 Insights

Why do we use === instead of == to compare enum cases?

Enums are objects, so === checks if they are exactly the same case instance. Using == might not work as expected. See step 3 in execution_table.

Can enum cases have values like strings or numbers?

Yes, PHP enums can be backed by strings or integers, but this example uses pure enums without values. This example shows simple cases only.

What happens if the condition in step 3 is false?

The echo statement would not run, so nothing would print. The script would end silently.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of $current after step 2?

A Status::Pending

B Status::Rejected

C Status::Approved

D undefined

💡 Hint

Check the variable_tracker row for $current after step 2.

At which step does the script print output?

A Step 3

B Step 4

C Step 2

D Step 5

💡 Hint

Look at the execution_table action that says 'Execute echo "Approved!"'.

If we changed $current to Status::Rejected, what would happen at step 3?

A Condition would be false

B Error occurs

C Condition would be true

D Script prints 'Approved!' anyway

💡 Hint

Compare $current value with Status::Approved in step 3 condition.

Concept Snapshot

PHP Enums let you define named cases as a type.
Use enum cases with EnumName::CaseName.
Compare enum cases with === for exact match.
Enums can be pure or backed by values.
Use enums to make code clearer and safer.

Full Transcript

This example shows how to define an enum called Status with three cases: Pending, Approved, and Rejected. We assign the variable $current to Status::Approved. Then we check if $current is exactly Status::Approved using the === operator. Since it is true, the script prints 'Approved!'. The script then ends. Enums help group related values and make code easier to read and maintain. Remember to use === to compare enum cases because they are objects. If the condition was false, the echo would not run and nothing would print.