PHP Access Modifiers

Access modifiers in PHP are essential keywords that define the accessibility of properties and methods within classes. They play a crucial role in controlling how objects of a class can interact with its members, ensuring a clear structure and encapsulation of data.

Key Concepts

• Access Modifiers: These determine the visibility of class members (properties and methods). There are three primary types:
  • Public: Members declared as public can be accessed from anywhere, both inside and outside the class.
  • Protected: Members declared as protected can be accessed only within the class itself and by inheriting classes.
  • Private: Members declared as private can only be accessed within the class that defines them. They are not accessible in inherited classes.

Examples

Public Access Modifier

class Example {
    public $name;

    public function display() {
        echo "Name: " . $this->name;
    }
}

$obj = new Example();
$obj->name = "John";
$obj->display(); // Output: Name: John

Protected Access Modifier

class ParentClass {
    protected $name;

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

class ChildClass extends ParentClass {
    public function display() {
        $this->setName("John");
        echo "Name: " . $this->name; // This will cause an error because $name is protected
    }
}

Private Access Modifier

class Example {
    private $name;

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

    public function display() {
        echo "Name: " . $this->name; // Accessible here
    }
}

$obj = new Example();
// $obj->name = "John"; // This will cause an error because $name is private
$obj->setName("John");
$obj->display(); // Output: Name: John

Summary

• Use public for members that need to be accessible everywhere.
• Use protected for members that should only be accessible within the class and its child classes.
• Use private for members that should only be accessible within the defined class.

Understanding these modifiers is crucial for encapsulating data and maintaining the integrity of your classes in PHP programming.