- var_dump: documentation ( source)
- array_column: documentation ( source)
<?php
$x = [
'foo' => ['a' => 1, 'b' => 2],
'bar' => ['a' => 3, 'b' => 4],
'fizz' => ['a' => 5, 'b' => 6],
'buzz' => ['a' => 7, 'b' => 8]
];
var_dump(array_column($x, 'b'));