Object-oriented programming

Classes allow you to define your own data types. All classes start with the class keyword followed by the name of the class and opening and closing curly braces.


class Car

To create an instance of a class, you use the new keyword in front of the class name with parentheses.

$car = new Car();

A class can define attributes and methods. An attribute is a piece of data stored on the class instance. You can define an attribute by adding the word public and a variable name inside the class definition.

class Bicycle
    public $color;

Then, when you create an instance of the class, you can set and use the attribute on the instance using ->.

$bike = new Bicycle();
$bike->color = 'Blue';
echo $bike->color . "\n";

An instance of a class is called an object. Congratulations! You are now performing object-oriented development.

$redBike = new Bicycle();
$redBike->color = 'Red';
echo $redBike->color . " Bike Object\n";

A method is a function attached to the class. You can add a method to a class by using the public keyword followed by the function. A method can access the attributes and methods of an object instance using the $this variable.

class Tricycle
    public $color;

    public function echoColor()
        echo $this->color . "\n";

You can execute a method on an object using the same -> arrow characters with parentheses after the method name.

$bike = new Tricycle();
$bike->color = 'Red';