PHP OOps
Object-Oriented Programming (OOP) in PHP allows you to create modular, reusable code through the use of objects and classes. Below are the core concepts of OOP in PHP with examples:
- Classes and Objects
- Properties and Methods
- Constructors and Destructors
- Inheritance
- Access Modifiers
- Static Methods and Properties
- Interfaces
- Abstract Classes
1. Classes and Objects
A class is a blueprint for creating objects. An object is an instance of a class.
<?php
class Car {
// Properties
public $color;
public $model;
// Methods
public function __construct($color, $model) {
$this->color = $color;
$this->model = $model;
}
public function message() {
return "My car is a " . $this->color . " " . $this->model . ".";
}
}
$myCar = new Car("red", "Toyota");
echo $myCar->message();
?>
Output:
My car is a red Toyota.
2. Properties and Methods
Properties are variables within a class, and methods are functions within a class.
<?php
class Person {
public $name;
public $age;
public function setName($name) {
$this->name = $name;
}
public function getName() {
return $this->name;
}
}
$person = new Person();
$person->setName("John");
echo $person->getName();
?>
Output:
John
3. Constructors and Destructors
Constructors are special methods that are called when an object is instantiated. Destructors are called when the object is destroyed.
<?php
class Animal {
public function __construct() {
echo "An animal has been created.<br>";
}
public function __destruct() {
echo "An animal has been destroyed.<br>";
}
}
$animal = new Animal();
?>
Output:
An animal has been created.
An animal has been destroyed.
4. Inheritance
Inheritance allows a class to inherit the properties and methods of another class.
<?php
class ParentClass {
public function parentMethod() {
echo "This is a method from the parent class.<br>";
}
}
class ChildClass extends ParentClass {
public function childMethod() {
echo "This is a method from the child class.<br>";
}
}
$child = new ChildClass();
$child->parentMethod();
$child->childMethod();
?>
Output:
This is a method from the parent class.
This is a method from the child class.
5. Access Modifiers
Access modifiers define the visibility of properties and methods. PHP has three access modifiers: public, protected, and private.
<?php
class Test {
public $publicProperty = "Public";
protected $protectedProperty = "Protected";
private $privateProperty = "Private";
public function publicMethod() {
echo $this->publicProperty . "<br>";
echo $this->protectedProperty . "<br>";
echo $this->privateProperty . "<br>";
}
}
$test = new Test();
echo $test->publicProperty . "<br>"; // Works
// echo $test->protectedProperty; // Error
// echo $test->privateProperty; // Error
$test->publicMethod();
?>
Output:
Public
Public
Protected
Private
6. Static Methods and Properties
Static methods and properties belong to the class itself rather than any object.
<?php
class StaticExample {
public static $staticProperty = "I'm static";
public static function staticMethod() {
return "I'm a static method";
}
}
echo StaticExample::$staticProperty . "<br>";
echo StaticExample::staticMethod();
?>
Output:
I'm static
I'm a static method
7. Interfaces
Interfaces allow you to define methods that must be implemented in any class that implements the interface.
<?php
interface AnimalInterface {
public function makeSound();
}
class Dog implements AnimalInterface {
public function makeSound() {
echo "Woof!<br>";
}
}
class Cat implements AnimalInterface {
public function makeSound() {
echo "Meow!<br>";
}
}
$dog = new Dog();
$dog->makeSound();
$cat = new Cat();
$cat->makeSound();
?>
Output:
Woof!
Meow!
8. Abstract Classes
Abstract classes cannot be instantiated and are meant to be extended by other classes. They can have abstract methods that must be implemented in the child classes.
<?php
abstract class Vehicle {
abstract public function startEngine();
public function describe() {
echo "This is a vehicle.<br>";
}
}
class Car extends Vehicle {
public function startEngine() {
echo "Starting car engine.<br>";
}
}
$car = new Car();
$car->describe();
$car->startEngine();
?>
Output:
This is a vehicle.
Starting car engine.
These are the fundamental concepts of PHP's object-oriented programming. Using these, you can create well-structured, modular, and reusable code.
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