Understanding public, protected, and private

Visibility keywords control which code can access properties and methods.

What It Does

Visibility keywords control which code can access properties and methods. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Start with the smallest meaningful working case.

<?php
class Account { public string $name = 'Ava'; protected int $level = 2; private string $token = 'internal'; public function level(): int { return $this->level; } }
$a = new Account(); echo $a->name . ':' . $a->level();

Example 2: Another Case

Examine the edge case and the observable result.

<?php
class BaseJob { protected function prefix(): string { return 'job'; } }
class EmailJob extends BaseJob { public function label(): string { return $this->prefix() . '-mail'; } }
echo (new EmailJob())->label();

Practical Example: Putting It to Use

Apply the technique to a small practical task.

<?php
final class Counter { private int $count = 0; public function add(): void { $this->count++; } public function value(): int { return $this->count; } }
$c = new Counter(); $c->add(); echo $c->value();

Important Behavior and Edge Cases

Visibility alone is not authorization: users must still be checked before sensitive actions.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• Visibility keywords control which code can access properties and methods.
• Visibility alone is not authorization: users must still be checked before sensitive actions.
• Encapsulation combines private state with public validated methods.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.