PHP Class Shape: Abstract method and subclass implementation

Last update on May 29 2025 13:08:02 (UTC/GMT +8 hours)

3. Abstract Shape with Subclasses

Write a PHP class called 'Shape' with an abstract method 'calculateArea()'. Create two subclasses, 'Triangle' and 'Rectangle', that implement the 'calculateArea()' method.

Sample Solution:

PHP Code :

<?php
abstract class Shape {
    abstract public function calculateArea();
}

class Triangle extends Shape {
    private $base;
    private $height;

    public function __construct($base, $height) {
        $this->base = $base;
        $this->height = $height;
    }

    public function calculateArea() {
        return 0.5 * $this->base * $this->height;
    }
}

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;
    }
}

$triangle = new Triangle(5, 7);
echo "Triangle Area: " . $triangle->calculateArea() . "</br>";

$rectangle = new Rectangle(4, 6);
echo "Rectangle Area: " . $rectangle->calculateArea() . "</br>";

?>

Sample Output:

Triangle Area: 17.5
Rectangle Area: 24

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP abstract class with multiple abstract methods, then implement these methods in several geometric shape subclasses.
Write a PHP program that creates an array of different Shape objects and calculates the total combined area.
Write a PHP script that uses polymorphism to call the calculateArea() method on various Shape subclass instances.
Write a PHP program that compares the areas of a Triangle and a Rectangle object created from the same set of dimensions.

Go to:

PREV : Circle Class.
NEXT : Resizable Interface with Square Class.

PHP Code Editor:

Contribute your code and comments through Disqus.