Access newly added key=>value in associative array during loop - php

Question

I am trying to add a key=>value pair to an array while using a foreach loop, when that value is added the foreach loop needs to process the new key=>value pair.
$array = array(
'one' => 1,
'two' => 2,
'three' => 3
);
foreach($array as $key => $value) {
if ($key == 'three') {
$array['four'] = 4;
} else if ($key == 'four') {
$array['five'] = 5;
}
}
If I print the array after the loop, I would expect to see all 5 kv's, but instead I only see this:
Array
(
[one] => 1
[two] => 2
[three] => 3
[four] => 4
)
Is there some way, when I add the fourth pair, to actually process it so the fifth pair gets added within that foreach loop (or another kind of loop?)

Answer 1

According to php documentation,
As foreach relies on the internal array pointer changing it within the loop may lead to unexpected behavior.
You cannot modify the array during foreach. However, an user posted an example of a regular while loop that does what you need: http://www.php.net/manual/en/control-structures.foreach.php#99909
I report it here
<?php
$values = array(1 => 'a', 2 => 'b', 3 => 'c');
while (list($key, $value) = each($values)) {
echo "$key => $value \r\n";
if ($key == 3) {
$values[4] = 'd';
}
if ($key == 4) {
$values[5] = 'e';
}
}
?>
the code above will output:
1 => a
2 => b
3 => c
4 => d
5 => e

Answer 2

That's because PHP will internally use it's own copy of the array pointer. You are iterating trough it's orginal key/values not through the modified array.
As the original array contains the key three, the first if statement will match, but not the second
Another simpler example is the fact, that this is not an infinite loop:
$array = array(1);
foreach($array as $val) {
$array []= $val +1;
}
var_dump($array);
Output:
array(2) {
[0] =>
int(1)
[1] =>
int(2)
}
However, the PHP documentation says not much to that:
As foreach relies on the internal array pointer changing it within the loop may lead to unexpected behavior.