How do I create objects from classes in PHP?
Jun 24, 2025 am 12:29 AM
To create an object in PHP, you must first define the class and then instantiate it with the new keyword. 1. Classes are blueprints of objects, defining properties and methods; 2. Create object instances using new; 3. Constructors are used to initialize different data; 4. Access properties and methods through ->; 5. Pay attention to access control of public, private, and protected; 6. Multiple independent instances can be created, each maintaining its state. For example, after defining the Car class, new Car('red') creates an object and passes a parameter, and $myCar->startEngine() calls the method, and each object does not affect each other. Mastering these helps build clearer, scalable applications.
In PHP, creating objects from classes is straightforward once you understand the basics of object-oriented programming (OOP). You define a class, then instantiate it using the new keyword. That's how you get an object.
Understanding Classes and Objects
A class in PHP is like a blueprint — it defines properties and methods that an object will have. An object is an instance of a class. Think of a class as a recipe and the object as the actual dish made from that recipe.
Here's a basic example:
class Car {
public $color = 'red';
public function startEngine() {
echo "Engine started!";
}
}To create an object from this class:
$myCar = new Car();
Now $myCar is an object based on the Car class and has access to its properties and methods.
Using Constructors for Custom Setup
Most of the time, you won't want every object to be exactly the same. That's where constructors come in handy. A constructor is a special method that runs when you create an object. It lets you pass values ??during instantiation.
Let's update our Car class:
class Car {
public $color;
public function __construct($color) {
$this->color = $color;
}
public function describe() {
echo "This car is $this->color.";
}
}Now when you create a car, you can specify the color:
$redCar = new Car('red'); $blueCar = new Car('blue'); $redCar->describe(); // Outputs: This car is red. $blueCar->describe(); // Outputs: This car is blue.
This way, each object can have different data while sharing the same structure.
Accessing Properties and Methods
Once an object is created, accessing its properties and methods is simple:
- Use
->to access properties or call methods.
For example:
echo $myCar->color; // Access property $myCar->startEngine(); // Call method
Be mindful of visibility:
-
publicmeans accessible from anywhere. -
privatemeans only accessible within the class itself. -
protectedmeans accessible within the class and any subclasses.
Visibility affects what you can do with the object outside of the class definition.
Creating Multiple Instances
You can create as many instances of a class as you need. Each one is separate from the others.
$car1 = new Car('black'); $car2 = new Car('white'); $car1->describe(); // This car is black. $car2->describe(); // This car is white.
Each object maintains its own state. Changing one doesn't affect the others.
Creating objects in PHP isn't complicated, but knowing how to work with them effectively opens the door to building more organized and scalable applications.
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