Online PHP editor | output for tK9Q9

<?php class DataStructure { private $data = []; public function __construct($data) { foreach (explode('|', $data) as $item_quantity) { list($quantity, $item) = explode(':', $item_quantity); $this->data[$item] = (int)$quantity; } } public function getItemQuantity($item) { return isset($this->data[$item]) ? $this->data[$item] : null; } public function setItemQuantity($item, $quantity) { $this->data[$item] = (int)$quantity; } public function __toString() { return implode('|', array_map(function ($item) { return $this->data[$item] . ':' . $item; }, array_keys($this->data))); } } $data = new DataStructure('3:1|8:2|5:3|4:4'); $data->setItemQuantity(4, '12'); var_dump($data->getItemQuantity(4)); var_dump($data->getItemQuantity(2)); var_dump($data->getItemQuantity(12));