Backend Php Memory Performance Interview Questions

$a = [1, 2, 3];
$b = $a;
$b[] = 4;
echo count($a);

What does this code print?

$a = 10;
$b = &$a;
$a = 20;
echo $b;

What does this code print?

$fruits = ['a' => 'apple', 'b' => 'banana', 'c' => 'cherry'];
unset($fruits['b']);
echo count($fruits);

What does this code print?

$x = 5;
unset($x);
var_dump(isset($x));

What does this code print?

function addItem($arr) {
    $arr[] = 99;
    return count($arr);
}
$list = [1, 2, 3];
$result = addItem($list);
echo count($list) . ' ' . $result;

What does this code print?

$nums = [1, 2, 3];
foreach ($nums as $n) {
    $n = $n * 10;
}
print_r($nums);

What does this code print?