[Applied] Build a Simple Inventory Management Tool

In this lesson you will combine the classes, arrays, and functions you have learned into a simple inventory management program, pulling everything together. This is for anyone searching for "PHP inventory management how to build".

Combine the classes, arrays, and functions you have learned so far into a program that tracks stock levels. A class holding an array as a property is a pattern that comes up constantly in real applications, from inventory to shopping carts.

The sample code gives the Inventory class an $items property holding products and quantities in an associative array, plus three methods: add(), remove(), and show(). Notice how the ?? operator handles a product that has not been registered yet.

A common stumbling block for beginners is taking in a program where several features interlock. Check one method at a time - add() first, then remove() - before following how they work together, and it becomes much easier to grasp.

Well done for getting this far. The PHP fundamentals from these 68 lessons apply directly to a wide range of real work, from web development to customising a CMS.

📖 Reference code

<?php
class Inventory {
    private $items = [];
    function add($name, $qty) {
        $this->items[$name] = ($this->items[$name] ?? 0) + $qty;
    }
    function remove($name, $qty) {
        if (isset($this->items[$name])) {
            $this->items[$name] -= $qty;
        }
    }
    function show() {
        foreach ($this->items as $name => $qty) {
            echo "$name: {$qty}\n";
        }
    }
}

$inv = new Inventory();
$inv->add("apple", 10);
$inv->add("orange", 5);
$inv->remove("apple", 3);
$inv->show();

✍️ Your code

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🧪 This site can't compile or run PHP directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).