Access Modifiers in PHP (public, private, protected)

Introduction

In Object-Oriented Programming, access modifiers control the visibility of properties and methods inside a class.

They determine:

• Who can access a property
• Who can call a method
• Whether data can be modified from outside the class

In PHP, there are three main access modifiers:

• public
• private
• protected

Understanding access modifiers is important because they help protect data and improve code security and structure.

Why Are Access Modifiers Important?

Without access control, anyone could change the internal data of an object. This could lead to unexpected behavior and security problems.

Access modifiers help you:

• Protect sensitive data
• Control how properties are accessed
• Prevent accidental changes
• Follow proper OOP principles
• Implement encapsulation

They make your code safer and more professional.

Public Access Modifier

What is public?

• Accessible from anywhere
• Can be used inside and outside the class

Public Example

<?php
class User {
    public $name;

    public function setName($name) {
        $this->name = $name;
    }
}
?>

Accessing Public Members

<?php
$user = new User();
$user->name = "Divyesh";
$user->setName("Divyesh");
?>

✔ Works fine
✔ No restriction

Private Access Modifier

What is private?

• Accessible only inside the same class
• Cannot be accessed from outside or child classes

Used to hide sensitive data.

Private Example

<?php
class User {
    private $password;

    public function setPassword($pass) {
        $this->password = $pass;
    }
}
?>

Trying to Access Private Property

<?php
$user = new User();
$user->password = "123456"; // ❌ Error
?>

❌ This will cause an error because $password is private.

Correct Way (Using Method)

<?php
$user->setPassword("123456");
?>

✔ Secure access

Why Private is Important (Encapsulation)

Encapsulation means hiding internal details and allowing access only through controlled methods.

For example:

• You should not allow users to directly change account balance
• Instead, provide deposit() and withdraw() methods

This prevents invalid or harmful data changes.

Protected Access Modifier

What is protected?

• Accessible inside the class
• Accessible in child (inherited) classes
• Not accessible from outside

Protected Example

<?php
class User {
    protected $role = "User";
}
?>

Child Class Access

<?php
class Admin extends User {
    public function getRole() {
        return $this->role;
    }
}

$admin = new Admin();
echo $admin->getRole();
?>

✔ Works because role is protected.

Outside Access

<?php
$admin = new Admin();
echo $admin->role; // ❌ Error
?>

❌ Not allowed

Difference Between Access Modifiers

Modifier	Same Class	Child Class	Outside Class
public	✅	✅	✅
protected	✅	✅	❌
private	✅	❌	❌

Why Access Modifiers Matter

They help you:

• Prevent accidental data modification
• Secure sensitive information
• Control how your class is used
• Follow encapsulation principle

Real-World Analogy

Think of a company:

• Public → Information available to everyone
• Private → Personal data accessible only by the owner
• Protected → Data accessible within the company hierarchy

This is how access control works in OOP as well.

Common Beginner Mistakes

• Forgetting to declare visibility (PHP requires it)
• Trying to access private properties directly
• Confusing protected with private
• Not using getter and setter methods
• Making everything public

A good practice is:
👉 Keep properties private
👉 Use public methods to control access

Practical Task

Create a class named BankAccount:

• Add a private property called balance
• Create a public method to deposit money
• Create a public method to withdraw money
• Try accessing balance directly and observe what happens

This will help you understand access control better.

Summary

• Access modifiers control visibility in PHP classes
• public allows access everywhere
• private allows access only inside the class
• protected allows access inside the class and child classes
• They help implement encapsulation and protect data

Access modifiers are essential for writing secure and structured OOP code.

In the next tutorial, we’ll learn about Inheritance in PHP.