PHP class with comparable interface

Last update on May 29 2025 13:10:25 (UTC/GMT +8 hours)

12. Product Class with Comparable Interface

Write a class called 'Product' with properties like 'name' and 'price'. Implement the 'Comparable' interface to compare products based on their prices.

Sample Solution:

PHP Code :

<?php
interface Comparable {
    public function compareTo($other);
}

class Product implements Comparable {
    private $name;
    private $price;

    public function __construct($name, $price) {
        $this->name = $name;
        $this->price = $price;
    }

    public function getName() {
        return $this->name;
    }

    public function getPrice() {
        return $this->price;
    }

    public function compareTo($other) {
        if ($other instanceof Product) {
            if ($this->price < $other->getPrice()) {
                return -1;
            } elseif ($this->price > $other->getPrice()) {
                return 1;
            } else {
                return 0;
            }
        } else {
            throw new Exception("Invalid comparison object.");
        }
    }
}

$product1 = new Product("Desktop", 1200);
$product2 = new Product("Laptop", 1000);

$result = $product1->compareTo($product2);

if ($result < 0) {
    echo $product1->getName() . " is cheaper than " . $product2->getName() . "</br>";
} elseif ($result > 0) {
    echo $product1->getName() . " is more expensive than " . $product2->getName() . "</br>";
} else {
    echo $product1->getName() . " and " . $product2->getName() . " have the same price.</br>";
}

?>

Sample Output:

Desktop is more expensive than Laptop

Explanation:

In the above exercise -

The Comparable interface declares a single method compareTo() that accepts another object for comparison.
The "Product" class implements the Comparable interface and defines the compareTo() method.
The Product class has two private properties: $name and $price, representing the product's name and price.
The constructor method __construct() is used to initialize the values of the properties when creating a new instance of the Product class.
The getName() and getPrice() methods retrieve name and price, respectively.
The compareTo() method compares two Product objects based on their prices. It returns -1, 0, or 1 indicating whether the current object is less than, equal to, or greater than the compared object.

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP class Product implementing a Comparable-like interface to allow products to be sorted by price.
Write a PHP script to create an array of Product objects, then sort them in ascending order by their price property.
Write a PHP function to compare two Product objects and return 1, -1, or 0 based on price difference.
Write a PHP program to display the details of the most expensive product from an array of Product objects after sorting.

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