- array_walk_recursive: documentation ( source)
<?php
$items = array('amount' => 50, 'amount' => 60, 'amount' => 100, 'amount' => 25, 'amount' => 30, 'amount' => 89, 'amount' => 90, 'amount' => 120, 'amount' => 16, 'amount' => 38);
$itemsSum = 0;
array_walk_recursive($items, function ($item) use (&$itemsSum) {
$itemsSum += 1;
});
echo $itemsSum;