Online PHP editor | output for l2W0e

<?php $array = [['user1' => 20], ['user2' => 30], 3 => ['user3' => 10]]; echo array_sum(array_column(array_map('array_values', $array), 0)); // reindex subarrays, isolate zero column, sum values echo "\n---\n"; array_walk_recursive($array, function($v)use(&$sum){ $sum += $v; }); // visit each leafnode, increase the $sum tally echo $sum; echo "\n---\n"; $total = 0; // without this declaration, you will generate: "Notice: Undefined variable" foreach ($array as $subarray) { foreach ($subarray as $v) { $total += $v; } } echo $total;