PHP OOP: Inheritance

Mastering PHP OOP Inheritance: Explore the Power of Object-Oriented Programming

Introduction:
Welcome to our toturial in PHP Object-Oriented Programming (OOP) – Inheritance. Inheritance is a fundamental concept in OOP, allowing classes to inherit properties and methods from parent classes, promoting code reuse and creating hierarchies of classes. In this lesson, we’ll dive deep into the principles of PHP OOP inheritance, covering everything from syntax to best practices.

In PHP, Object-Oriented Programming (OOP) allows you to create classes that can inherit properties and methods from other classes. This is known as inheritance, and it is a fundamental concept in OOP that promotes code reusability and abstraction.

Here’s an example of inheritance in PHP:

<?php
// Parent class
class Vehicle {
protected $brand;

public function __construct($brand) {
$this->brand = $brand;
}

public function start() {
echo "Starting the {$this->brand}\n";
}
}

// Child class inheriting from Vehicle
class Car extends Vehicle {
private $model;

public function __construct($brand, $model) {
parent::__construct($brand);
$this->model = $model;
}

public function drive() {
echo "Driving the {$this->brand} {$this->model}\n";
}
}

// Creating instances of the classes
$car = new Car("Toyota", "Camry");

// Accessing methods from parent and child classes
$car->start(); // Output: Starting the Toyota
$car->drive(); // Output: Driving the Toyota Camry
?>

Explanation:

•  In this example Vehicle is the parent class, which has a property $brand and a method start().
• Car is the child class that inherits from Vehicle. It adds its own property $model and method drive().
• When creating an instance of Car, we call the constructor of the parent class using parent::__construct($brand), passing the $brand argument.
• We can access both start() method from the parent class and drive() method from the child class using the instance of Car.
• Inheritance allows you to create a hierarchy of classes where child classes can inherit and extend the functionality of parent classes.

step by step how to use PHP OOP – Inheritance?

Here’s a step-by-step guide on how to use PHP Object-Oriented Programming (OOP) with Inheritance:

Step 1: Define the Parent Class

Start by defining a parent class. This class will contain properties and methods that you want to be inherited by child classes.

class Animal {
protected $species;

public function __construct($species) {
$this->species = $species;
}

public function eat() {
echo "The {$this->species} is eating.\n";
}
}

Step 2: Create a Child Class

• We will create a child class that extends the parent class.
• This child class will inherit all properties and methods from the parent class.

class Dog extends Animal {
public function bark() {
echo "The {$this->species} is barking.\n";
}
}

Step 3: Instantiate Objects

Instantiate objects of both the parent and child classes.

$animal = new Animal("Lion");
$dog = new Dog("Dog");

Step 4: Accessing Inherited Methods

Access methods from both the parent and child classes using the objects we created.

$animal->eat(); // Output: The Lion is eating.
$dog->eat(); // Output: The Dog is eating.

$dog->bark(); // Output: The Dog is barking.

Step 5: Extend Functionality

we can add additional methods or properties to the child class.

class Dog extends Animal {
public function bark() {
echo "The {$this->species} is barking.\n";
}

public function fetch() {
echo "The {$this->species} is fetching.\n";
}
}

Step 6: Utilizing Constructor Inheritance (Optional)

If we want to utilize the constructor of the parent class in the child class, call it explicitly using parent::__construct().

class Dog extends Animal {
public function __construct($species) {
parent::__construct($species);
}

// Other methods here...
}

Step 7: Creating and Useing Instances

we will create instances of the child class and use their methods.

$dog = new Dog("Golden Retriever");
$dog->eat(); // Output: The Golden Retriever is eating.
$dog->bark(); // Output: The Golden Retriever is barking.
$dog->fetch(); // Output: The Golden Retriever is fetching.

we’ve successfully used PHP OOP with Inheritance.
This allows for code reuse and promotes a more organized and modular approach to programming.

Complete example about PHP OOP with Inheritance

• Here is a complete PHP code example embedded in a web page.
• This example shows PHP Object-Oriented Programming (OOP) with Inheritance.
• We’ll provide explanations along with each part of the code.

<!DOCTYPE html>
<html>
<head>
<title>PHP OOP - Inheritance Example</title>
</head>
<body>

<?php
// Step 1: Defining the Parent Class
class Animal {
protected $species;

public function __construct($species) {
$this->species = $species;
}

public function eat() {
echo "The {$this->species} is eating.<br>";
}
}

// Step 2: Creating a Child Class
class Dog extends Animal {
public function bark() {
echo "The {$this->species} is barking.<br>";
}
}

// Step 3: Instantiate Objects
$animal = new Animal("Lion");
$dog = new Dog("Dog");

// Step 4: Accessing Inherited Methods
echo "<strong>Animal:</strong><br>";
$animal->eat(); // Output: The Lion is eating.

echo "<br><strong>Dog:</strong><br>";
$dog->eat(); // Output: The Dog is eating.
$dog->bark(); // Output: The Dog is barking.
?>

</body>
</html>

Explanation:

Step 1:
We define a parent class Animal with a constructor method __construct() and a method eat(). The __construct() method initializes the $species property, and eat() method describes the eating behavior of the animal.

Step 2:
We create a child class Dog that extends the Animal class. The Dog class inherits the properties and methods of the Animal class and adds its own method bark().

Step 3:
We instantiate objects of both the parent ($animal) and child ($dog) classes.

Step 4:
We access the inherited methods using the objects created. We shows that both the parent and child classes have access to the eat() method.
The child class Dog also has access to its own method bark().

This code can be saved as a .php file and run on a server with PHP support. When you open the page in a web browser, we’ll see the output showing inheritance in action, with the animal and dog behaviors displayed accordingly.

PHP – Inheritance and the Protected Access Modifier

• In PHP, the protected access modifier is used to restrict the visibility of properties and methods within a class and its child classes (i.e., classes that extend it).
• This means that properties and methods marked as protected can be accessed within the class itself and any child classes, but not from outside the class hierarchy.

Let’s show how protected works in inheritance with an example:

<?php
class Vehicle {
protected $brand;

public function __construct($brand) {
$this->brand = $brand;
}

protected function startEngine() {
echo "Starting the {$this->brand} engine.\n";
}
}

class Car extends Vehicle {
public function startCar() {
// We can access the protected property $brand and protected method startEngine() within the child class.
echo "Starting the {$this->brand} car.\n";
$this->startEngine();
}
}

// Creating an instance of the child class
$car = new Car("Toyota");

// Accessing a public method that internally accesses a protected method and property
$car->startCar(); // Output: Starting the Toyota car. Starting the Toyota engine.
?>

Explanation:

In this example:

• The Vehicle class has a protected property $brand and a protected method startEngine().
• The Car class extends Vehicle.
• Since these properties and methods are marked as protected, the Car class can access them directly.
• We instantiate a Car object and call its startCar() method. Inside startCar(), we access both the protected property $brand and the protected method startEngine() from the parent class Vehicle.
• Outside of the class hierarchy, the protected properties and methods are not accessible.
• Using the protected access modifier in inheritance helps encapsulate the internal workings of a class, allowing child classes to have access to necessary functionality while still maintaining encapsulation and data integrity.

step by step How to use:PHP – Inheritance and the Protected Access Modifier

Here’s a step-by-step guide on how to use PHP inheritance with the protected access modifier:

Step 1: Define a Parent Class

Start by defining a parent class with some protected properties and methods.

class Vehicle {
protected $brand;

protected function startEngine() {
echo "Starting the engine.\n";
}
}

Step 2: Create a Child Class

• we will create a child class that extends the parent class.
• The child class will inherit the protected properties and methods.

class Car extends Vehicle {
public function startCar() {
// We can access the protected property and method from the parent class here.
echo "Starting the car.\n";
$this->startEngine();
}
}

Step 3: Instantiate Objects

How to instantiate objects of both the parent and child classes?

$vehicle = new Vehicle();
$car = new Car();

Step 4: Access Protected Members

How to access the protected properties and methods within the child class?

$car->startCar(); // Output: Starting the car. Starting the engine.

Step 5: Restricted Access Outside Class Hierarchy

Outside the class hierarchy, the protected members are not accessible.

// Trying to access a protected property from outside the class hierarchy will result in an error.
// echo $vehicle->brand; // This would cause an error.

Complete Example

Here’s the complete code:

<?php
class Vehicle {
protected $brand;

protected function startEngine() {
echo "Starting the engine.\n";
}
}

class Car extends Vehicle {
public function startCar() {
echo "Starting the car.\n";
$this->startEngine();
}
}

// Instantiate objects
$vehicle = new Vehicle();
$car = new Car();

// Access protected members
$car->startCar(); // Output: Starting the car. Starting the engine.

// Trying to access protected members from outside the class hierarchy will result in an error.
// echo $vehicle->brand; // This would cause an error.
?>

We’ve successfully used PHP inheritance with the protected access modifier. This helps in encapsulating class internals while allowing child classes to access them for necessary functionality.

PHP – Overriding Inherited Methods

In PHP, overriding inherited methods allows child classes to provide their own implementation of a method that is already defined in the parent class. This allows for customization of behavior in child classes while maintaining the inheritance hierarchy.

We will go through a step-by-step example of how to override inherited methods in PHP:

Step 1: Define a Parent Class

Start by defining a parent class with a method that you want to override in child classes.

class Animal {
public function makeSound() {
echo "Generic animal sound.\n";
}
}

Step 2: Create a Child Class

• we will create a child class that extends the parent class.
• we can then override the method defined in the parent class with a new implementation in the child class.

class Dog extends Animal {
public function makeSound() {
echo "Woof woof!\n";
}
}

Step 3: Instantiate Objects

we will Instantiate objects of both the parent and child classes.

$animal = new Animal();
$dog = new Dog();

Step 4: Access Methods

Access the methods from both the parent and child classes.

$animal->makeSound(); // Output: Generic animal sound.
$dog->makeSound(); // Output: Woof woof!

Here’s the complete code:

<?php
class Animal {
public function makeSound() {
echo "Generic animal sound.\n";
}
}

class Dog extends Animal {
public function makeSound() {
echo "Woof woof!\n";
}
}

// Instantiate objects
$animal = new Animal();
$dog = new Dog();

// Access methods
$animal->makeSound(); // Output: Generic animal sound.
$dog->makeSound(); // Output: Woof woof!
?>

We’ve successfully overridden an inherited method in PHP. This allows child classes to provide their own implementation of methods defined in the parent class, enabling customization and specialization of behavior.

complete code abot  Overriding Inherited Methods

• Here is a complete PHP code example embedded in a web page.
• This example demonstrates how to override inherited methods in PHP. I’ll provide explanations along with each part of the code.

<!DOCTYPE html>
<html>
<head>
<title>PHP - Overriding Inherited Methods</title>
</head>
<body>

<?php
// Step 1: Define a Parent Class
class Animal {
// Method to be overridden
public function makeSound() {
echo "Generic animal sound.<br>";
}
}

// Step 2: Create a Child Class
class Dog extends Animal {
// Override the method from the parent class
public function makeSound() {
echo "Woof woof!<br>";
}
}

// Step 3: Instantiate Objects
$animal = new Animal();
$dog = new Dog();

// Step 4: Access Methods
echo "<strong>Animal:</strong><br>";
$animal->makeSound(); // Output: Generic animal sound.

echo "<br><strong>Dog:</strong><br>";
$dog->makeSound(); // Output: Woof woof!
?>

</body>
</html>

Explanation:
Step 1:
We define a parent class Animal with a method makeSound() that we intend to override in the child class.

Step 2:
We create a child class Dog that extends Animal. Within Dog, we define makeSound() again, effectively overriding the method inherited from Animal.

Step 3:
We instantiate objects of both the parent ($animal) and child ($dog) classes.

Step 4:

We access the overridden methods using the objects created. The makeSound() method behaves differently for the parent (Animal) and child (Dog) objects.

This code can be saved as a .php file and run on a server with PHP support. When you open the page in a web browser, you’ll see the output demonstrating the overridden methods in action, with different sounds being produced for the animal and the dog.

How to use The final Keyword in PHP OOP ?

PHP – The final Keyword

In PHP, the final keyword is used to prevent further inheritance or overriding of classes, methods, or properties. When a class, method, or property is declared as final, it cannot be extended or overridden by any child classes.

Explore how to use the final keyword with classes, methods, and properties:

1. Final Class:

final class BaseClass {
// Class implementation
}

In this example, BaseClass is marked as final, so it cannot be extended by any other class.

2. Final Method:

class ParentClass {
final public function someMethod() {
// Method implementation
}
}

class ChildClass extends ParentClass {
// Attempting to override a final method will result in an error.
// public function someMethod() {
// // Method implementation
// }
}

Here, someMethod() in ParentClass is marked as final, so it cannot be overridden by any child class.

3. Final Property:

class MyClass {
final public $someProperty = 'value';
}

In this example, $someProperty is marked as final, so it cannot be overridden or re-declared in any child class.

Important Notes:
The final keyword can be used in conjunction with the abstract keyword. However, it cannot be used with the abstract keyword on the same element (e.g., a class cannot be both final and abstract).

Attempting to extend a final class, override a final method, or re-declare a final property will result in a fatal error.

Using final helps in enforcing certain aspects of your class design, particularly when you want to prevent further extension or modification of specific elements.

Here’s a complete example showing the use of the final keyword:

<?php
class BaseClass {
final public function someMethod() {
echo "This method cannot be overridden.\n";
}
}

class ChildClass extends BaseClass {
// Attempting to override a final method will result in an error.
// public function someMethod() {
// echo "This method cannot be overridden.\n";
// }
}

// Instantiating objects
$base = new BaseClass();
$child = new ChildClass();

// Accessing the method
$base->someMethod(); // Output: This method cannot be overridden.
?>

In this example, attempting to override the someMethod() in ChildClass will result in a fatal error due to its final declaration in BaseClass.

Step by step how to use PHP – The final Keyword ?

Here is a step-by-step guide along with a complete code example showing the use of the final keyword in PHP:

Step 1: Define a Parent Class with a Final Method

Start by defining a parent class with a final method:

<?php
class ParentClass {
final public function finalMethod() {
echo "This method is final and cannot be overridden.\n";
}
}
?>

Step 2: Attempt to Override the Final Method

Attempt to override the final method in a child class:

<?php
class ChildClass extends ParentClass {
// Attempting to override a final method will result in an error.
// public function finalMethod() {
// echo "Trying to override the final method.\n";
// }
}
?>

Step 3: Instantiate Objects and Access Methods

Instantiate objects of both the parent and child classes and access the final method:

<?php
// Instantiate objects
$parent = new ParentClass();
$child = new ChildClass();

// Access the final method
$parent->finalMethod(); // Output: This method is final and cannot be overridden.
?>

Here’s the complete code example:

<?php
// Step 1: Define a Parent Class with a Final Method
class ParentClass {
final public function finalMethod() {
echo "This method is final and cannot be overridden.\n";
}
}

// Step 2: Attempt to Override the Final Method
class ChildClass extends ParentClass {
// Attempting to override a final method will result in an error.
// public function finalMethod() {
// echo "Trying to override the final method.\n";
// }
}

// Step 3: Instantiate Objects and Access Methods
// Instantiate objects
$parent = new ParentClass();
$child = new ChildClass();

// Access the final method
$parent->finalMethod(); // Output: This method is final and cannot be overridden.
?>

In this example, attempting to override the finalMethod() in ChildClass is commented out, as it will result in a fatal error due to its final declaration in ParentClass.

complete code example in web page

Here is the complete PHP code example embedded in a web page, demonstrating the use of the final keyword:

<!DOCTYPE html>
<html>
<head>
<title>PHP - The final Keyword Example</title>
</head>
<body>

<?php
// Step 1: Define a Parent Class with a Final Method
class ParentClass {
final public function finalMethod() {
echo "This method is final and cannot be overridden.<br>";
}
}

// Step 2: Attempt to Override the Final Method
class ChildClass extends ParentClass {
// Attempting to override a final method will result in an error.
// public function finalMethod() {
// echo "Trying to override the final method.<br>";
// }
}

// Step 3: Instantiate Objects and Access Methods
// Instantiate objects
$parent = new ParentClass();
$child = new ChildClass();

// Access the final method
$parent->finalMethod(); // Output: This method is final and cannot be overridden.
?>

</body>
</html>

This code can be saved as a .php file and run on a server with PHP support. When you open the page in a web browser, you’ll see the output demonstrating the use of the final keyword. The attempt to override the final method in ChildClass is commented out to avoid a fatal error.

A complete project about PHP OOP – Inheritance with explanation

• We will go to create a simple PHP project demonstrating PHP OOP (Object-Oriented Programming) with Inheritance.
• In this project, we’ll create a base class Vehicle and a child class Car that inherits from it.
• The Vehicle class will have a property and a method, and the Car class will inherit those members and also have its own properties and methods.

Project Structure:

php-oop-inheritance/
│
├── classes/
│ ├── Vehicle.php
│ └── Car.php
│
└── index.php

Step 1: Defining the Vehicle Class

we will Create a file named Vehicle.php inside the classes/ directory:

Vehicle.php:

<?php
class Vehicle {
protected $brand;

public function __construct($brand) {
$this->brand = $brand;
}

public function start() {
return "Starting the $this->brand.\n";
}
}
?>

Step 2: Defining the Car Class

Create another file named Car.php inside the classes/ directory:

Car.php:

<?php
require_once('Vehicle.php');

class Car extends Vehicle {
private $model;

public function __construct($brand, $model) {
parent::__construct($brand);
$this->model = $model;
}

public function drive() {
return "Driving the $this->brand $this->model.\n";
}
}
?>

Step 3: Implement the Index File

we will Create an index.php file in the project root directory to use the classes:

index.php:

<!DOCTYPE html>
<html>
<head>
<title>PHP OOP - Inheritance</title>
</head>
<body>

<?php
// Autoload classes
spl_autoload_register(function ($class_name) {
include 'classes/' . $class_name . '.php';
});

// Create instances
$car = new Car("Toyota", "Camry");

// Access inherited methods
echo "<p>" . $car->start() . "</p>"; // Output: Starting the Toyota.
echo "<p>" . $car->drive() . "</p>"; // Output: Driving the Toyota Camry.
?>

</body>
</html>

Explanation:

Step 1: We define the Vehicle class with a protected property $brand and a method start().

Step 2: We define the Car class that extends the Vehicle class. It adds its own property $model and method drive(). We include the Vehicle.php file to ensure the parent class is available.

Step 3: We autoload the classes using spl_autoload_register(). Then we create an instance of Car and access its inherited methods to start and drive the car.

Running the Project:

Place all files in the project structure.
Make sure your web server is running and configured to serve PHP files.
Open index.php in your web browser.
You should see the output showing inheritance in action, with the car being started and driven.

Another project about PHP OOP – Inheritance

 let’s create another PHP project showing inheritance, but this time let’s create a more abstract example. We’ll have a base class Shape representing geometric shapes, and two child classes Rectangle and Circle representing specific types of shapes. Each shape will have its own properties and methods.

Project Structure:

php-shape-inheritance/
│
├── classes/
│ ├── Shape.php
│ ├── Rectangle.php
│ └── Circle.php
│
└── index.php

Step 1: Defining the Shape Class

Create a file named Shape.php inside the classes/ directory:

Shape.php:

<?php
class Shape {
protected $color;

public function __construct($color) {
$this->color = $color;
}

public function getColor() {
return $this->color;
}

public function getArea() {
// Abstract method to be implemented by child classes
}
}
?>

Step 2: Defining the Rectangle Class

Create a file named Rectangle.php inside the classes/ directory:

Rectangle.php:

<?php
require_once('Shape.php');

class Rectangle extends Shape {
protected $width;
protected $height;

public function __construct($color, $width, $height) {
parent::__construct($color);
$this->width = $width;
$this->height = $height;
}

public function getArea() {
return $this->width * $this->height;
}
}
?>

Step 3: Defining the Circle Class

we will Create a file named Circle.php inside the classes/ directory:

Circle.php:

<?php
require_once('Shape.php');

class Circle extends Shape {
protected $radius;

public function __construct($color, $radius) {
parent::__construct($color);
$this->radius = $radius;
}

public function getArea() {
return pi() * pow($this->radius, 2);
}
}
?>

Step 4: Implement the Index File

we will Create an index.php file in the project root directory to use the classes:

index.php:

<!DOCTYPE html>
<html>
<head>
<title>PHP - Shape Inheritance</title>
</head>
<body>

<?php
// Autoload classes
spl_autoload_register(function ($class_name) {
include 'classes/' . $class_name . '.php';
});

// Create instances
$rectangle = new Rectangle("blue", 5, 4);
$circle = new Circle("red", 3);

// Access inherited methods
echo "<p>The area of the rectangle is: " . $rectangle->getArea() . "</p>"; // Output: The area of the rectangle is: 20
echo "<p>The area of the circle is: " . $circle->getArea() . "</p>"; // Output: The area of the circle is: 28.274333882308
?>

</body>
</html>

Explanation:

Step 1: We define the Shape class with a protected property $color and a method getColor(). It also has an abstract method getArea() which will be implemented by child classes.

Step 2: We define the Rectangle class that extends the Shape class. It adds its own properties $width and $height and implements the getArea() method to calculate the area of a rectangle.

Step 3: We define the Circle class that extends the Shape class. It adds its own property $radius and implements the getArea() method to calculate the area of a circle.

Step 4: In index.php, we autoload the classes using spl_autoload_register(), create instances of Rectangle and Circle, and access their inherited getArea() methods to calculate their respective areas.

Running the Project:

Place all files in the project structure.
Make sure your web server is running and configured to serve PHP files.
Open index.php in your web browser.
You should see the output displaying the calculated areas of a rectangle and a circle.

Quiz about PHP OOP – Inheritance

we will create a multiple-choice quiz about PHP OOP – Inheritance:

Multiple-Choice Quiz about PHP OOP – Inheritance :

1-What is inheritance in PHP OOP?

A) A mechanism to allow a class to inherit properties and methods from another class.
B) A way to create new classes.
C) A method to access private properties.
D) A function to override parent class methods.

2-Which keyword is used to indicate inheritance in PHP?

A) extends
B) inherit
C) include
D) inheritFrom

3-In PHP, which access modifier allows a property or method to be accessible only within the class itself and its child classes?

A) public
B) private
C) protected
D) internal

4-What happens if you attempt to override a final method in a child class?

A) It will result in a warning.
B) It will result in a fatal error.
C) It will execute both the parent and child methods.
D) It will override the parent method.

5-Which of the following is not true about inheritance?

A) Child classes can override parent class methods.
B) It promotes code reuse.
C) It increases coupling between classes.
D) It allows for specialization of behavior.

6-Which keyword is used to mark a method as final in PHP?

A) final
B) end
C) finish
D) close

7-In PHP, which method is automatically called in a child class when it is instantiated?

A) __construct()
B) __init()
C) start()
D) create()

8-What does the keyword parent:: do in PHP?

A) It calls a method from the parent class.
B) It creates a new instance of the parent class.
C) It deletes the parent class.
D) It checks if the current class is a child class.

9-Which of the following statements is true about abstract classes in PHP?

A) Abstract classes cannot have abstract methods.
B) Abstract classes cannot be inherited.
C) Abstract methods must be implemented in child classes.
D) Abstract classes cannot have properties.

10-What is the purpose of using spl_autoload_register() in PHP OOP?

A) To manually load classes one by one.
B) To define autoloading rules for classes.
C) To unload classes after use.
D) To prevent inheritance.

11-Which method is called when an object is being converted to a string in PHP?

A) __tostring()
B) __stringify()
C) __convert()
D) __string()

12-In PHP, how do you prevent a class from being inherited?

A) Use the final keyword before the class declaration.
B) Use the private keyword before the class declaration.
C) Use the protected keyword before the class declaration.
D) Use the static keyword before the class declaration.

13-Which of the following is a benefit of inheritance in PHP OOP?

A) It increases code complexity.
B) It allows for tighter coupling between classes.
C) It promotes code reusability.
D) It eliminates the need for encapsulation.

14-When is it appropriate to use inheritance in PHP OOP?

A) When classes have unrelated functionality.
B) When there is no need for code reuse.
C) When classes share common behavior.
D) When you want to create new classes from scratch.

15-Which keyword is used to access the parent class constructor within a child class constructor in PHP?

A) super
B) base
C) parent
D) this

Explanation:
A) A mechanism to allow a class to inherit properties and methods from another class. – Inheritance allows a class to inherit properties and methods from another class, promoting code reuse and creating a hierarchy of classes.
A) extends – The extends keyword is used in PHP to indicate inheritance.
C) protected – The protected access modifier in PHP allows a property or method to be accessible only within the class itself and its child classes.
B) It will result in a fatal error. – Attempting to override a final method in a child class will result in a fatal error.
C) It increases coupling between classes. – Inheritance can increase coupling between classes, making them more dependent on each other.
A) final – The final keyword is used to mark a method as final in PHP, preventing it from being overridden in child classes.
A) __construct() – The __construct() method is automatically called in a child class when it is instantiated.
A) It calls a method from the parent class. – The parent:: keyword in PHP is used to call a method from the parent class within a child class.
C) Abstract methods must be implemented in child classes. – Abstract classes in PHP can have abstract methods, which must be implemented in child classes.
B) To define autoloading rules for classes. – spl_autoload_register() in PHP is used to define autoloading rules for classes, allowing them to be loaded automatically when needed.
A) __tostring() – The __tostring() method is called when an object is being converted to a string in PHP.
A) Use the final keyword before the class declaration. – To prevent a class from being inherited in PHP, you can use the final keyword before the class declaration.
C) It promotes code reusability. – Inheritance in PHP OOP promotes code reusability by allowing classes to inherit properties and methods from other classes.
C) When classes share common behavior. – It is appropriate to use inheritance in PHP OOP when classes share common behavior and can benefit from code reuse.
C) parent – The parent keyword is used to access the parent class constructor within a child class constructor in PHP.