<?php
$output = null;

$ids = [10, 22, 15, 45, 67, 33];
$users = ['user2', 'user1', 'user3'];

// count
$output = count($ids);

// sort
sort($ids);
sort($users);

// rsort
rsort($ids);
rsort($users);

// array_push
array_push($ids, 100);
array_push($users, 'user4');

// array_pop
array_pop($ids);
array_pop($users);

// array_shift
array_shift($ids);
array_shift($users);

// array_unshift
array_unshift($ids, 100);
array_unshift($users, 'user3');

// array_slice
$ids2 = array_slice($ids, 2, 3);
// var_dump($ids2);

// array_splice
array_splice($ids, 1, 1, 'New ID');
array_splice($users, 0, 1, 'New User');

// array_sum
$output = 'Sum of IDs: ' . array_sum($ids);

// array_search
$output = 'User 2 is at index: ' . array_search('user2', $users);

array_push($users, 'user3');
// in_array
$output = 'User 3 Exists: ' . in_array('user3', $users);

// explode
$tags = 'tech,code,programming';
$tagsArr = explode(',', $tags);
// var_dump($tagsArr);

// implode
$output = implode(', ', $users);

// PHP documentation](https://www.php.net/manual/en/ref.array.php).
?>