<?php

$availableProducts = ['Laptop', 'Mouse', 'Keyboard', 'Monitor', 'Webcam'];
$customerOrder = ['Laptop', 'Keyboard', 'Webcam', 'Headphones'];

// Find products in stock that are NOT in the customer's order
$productsInStockNotOrdered = array_diff($availableProducts, $customerOrder);
echo "Products in stock but not ordered:
";
print_r($productsInStockNotOrdered);
/* Output:
Array
(
    [1] => Mouse
    [3] => Monitor
)
*/

// Find items in the customer's order that are NOT in stock
$productsOrderedButNotInStock = array_diff($customerOrder, $availableProducts);
echo "
Products ordered but not in stock:
";
print_r($productsOrderedButNotInStock);
/* Output:
Array
(
    [3] => Headphones
)
*/

$userPermissionsA = ['read', 'write', 'delete'];
$userPermissionsB = ['read', 'create', 'write'];

// Permissions unique to User A
$uniqueToUserA = array_diff($userPermissionsA, $userPermissionsB);
echo "
Permissions unique to User A:
";
print_r($uniqueToUserA);
/* Output:
Array
(
    [2] => delete
)
*/

// Permissions unique to User B
$uniqueToUserB = array_diff($userPermissionsB, $userPermissionsA);
echo "
Permissions unique to User B:
";
print_r($uniqueToUserB);
/* Output:
Array
(
    [1] => create
)
*/

// Example with associative arrays, comparing keys AND values
$userProfileOld = ['id' => 1, 'name' => 'Jane Doe', 'email' => 'jane@example.com', 'status' => 'active'];
$userProfileNew = ['id' => 1, 'name' => 'Jane Smith', 'email' => 'jane@example.com', 'role' => 'admin'];

// array_diff_assoc compares both keys and values
$changedProperties = array_diff_assoc($userProfileOld, $userProfileNew);
echo "
Properties changed or present only in old profile (key-value comparison):
";
print_r($changedProperties);
/* Output:
Array
(
    [name] => Jane Doe
    [status] => active
)
*/

?>