The documentation states "This iterator allows to unset and modify values and keys while iterating over Arrays and Objects". But if you pass an array to the constructor, the iterator works with a copy of that array, so the modifications will not be written back to that initial array. ArrayObject behaves the same way.
If you want an iterator that writes back to the array, you can use this function:
<?php
function &getArrayIterator(array &$a): Iterator {
foreach ($a as $k => &$v) {
yield $k => $v;
}
}
?>
Usage:
<?php
$array = [1 => 'a', 2 => 'b'];
$iterator = getArrayIterator($array);
foreach ($iterator as &$value) {
$value .= 'x';
}
var_dump($array);
var_dump($iterator);
?>
Comparison with plain array, ArrayIterator and ArrayObject:
<?php
$array1 = [1 => 'a', 2 => 'b'];
$array2 = [1 => 'a', 2 => 'b'];
$array3 = [1 => 'a', 2 => 'b'];
foreach ($array1 as &$value) {
$value .= 'x';
}
$iterator2 = new ArrayIterator($array2);
foreach ($iterator2 as &$value) {
$value .= 'x';
}
$iterator3 = new ArrayObject($array3);
foreach ($iterator3 as &$value) {
$value .= 'x';
}
var_dump($array1);
var_dump($array2);
var_dump($iterator2);
var_dump($array3);
var_dump($iterator3);
?>
