Introduction to object-oriented programming (OOP) concepts in PHP | Php IDE

<?php
// Define a superclass
class Shape {
    public function calculateArea() {
        return 0;
    }
}

// Define subclasses that inherit from Shape
class Circle extends Shape {
    private $radius;

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

public function calculateArea() {
        return pi() * $this->radius * $this->radius;
    }
}

class Rectangle extends Shape {
    private $length;
    private $width;

public function __construct($length, $width) {
        $this->length = $length;
        $this->width = $width;
    }

public function calculateArea() {
        return $this->length * $this->width;
    }
}

// Create objects of both classes
$circle = new Circle(5);
$rectangle = new Rectangle(4, 6);

// Call the calculateArea method
echo "Area of the circle: " . $circle->calculateArea();       // Output: Area of the circle: 78.539816339745
echo "Area of the rectangle: " . $rectangle->calculateArea(); // Output: Area of the rectangle: 24
?>