PHP var_dump and loop giving different results - php

Question

I have the following code:
var_dump($cursor);
foreach($cursor as $obj) {
echo "<div class='item' id='" . $obj['_id'] . "'>";
echo "<span class='listnick'>" . $obj['nick'] . "</span>";
echo "</div>";
}
The result of var_dump is the following:
array(2) {
[0]=>
&array(9) {
["_id"]=>
object(MongoId)#9 (1) {
["$id"]=>
string(24) "50af8dcd9cc231534400000c"
}
["nick"]=>
string(6) "safari"
}
[1]=>
array(9) {
["_id"]=>
object(MongoId)#8 (1) {
["$id"]=>
string(24) "50af8dca9cc2315644000009"
}
["nick"]=>
string(6) "chrome"
}
}
so obviously the foreach should print out "safari" and "chrome", but the problem is really weird:
Sometimes it returns "safari" twice and omits "chrome", and viceversa for the other client. I tried putting the var_dump and the foreach loop near to be sure they are the SAME and there are no changes in the object between the two commands, but really I got no idea what's going on.
Any help? Thanks in advance.

Answer 1

Notice how safari is a reference to an array: &array.
This might result from having a foreach where $obj is a reference:
foreach($cursor as &$obj) {
..
}
//unset($obj);
In PHP, the scope of $obj does not end with execution of the loop, so you should do an unset whenever you looped using a reference.
This might also result from using the reference assignment somewhere:
$cursor[] =& $safari;

Answer 2

This are 2 difference codes ... One is using & reference which would modify the array output and the other is not
array(2) {
[0]=>
&array(9) {
^----------------------------- Reference sign
["_id"]=>
object(MongoId)#9 (1) {
["$id"]=>
string(24) "50af8dcd9cc231534400000c"
}
["nick"]=>
string(6) "safari"
}
Topical example of what happened
$a = $b = array(array("_id" => new MongoId(),"nick" => "chrome"));
foreach ( $a as $k => &$v )
$k == "nick" and $v['nick'] = "Safari";
foreach ( $b as $k => $v )
$k == "nick" and $v['nick'] = "Safari";
var_dump($a);
var_dump($b);
Output
array (size=1)
0 =>
&array (size=2)
'_id' =>
object(MongoId)[1]
public '$id' => string '50af93a2a5d4ff5015000011' (length=24)
'nick' => string 'Safari' (length=6) <------ changed
array (size=1)
0 =>
array (size=2)
'_id' =>
object(MongoId)[2]
public '$id' => string '50af93a2a5d4ff5015000012' (length=24)
'nick' => string 'chrome' (length=6) <------- not changed
Can you see that one if the Nick is modified not the two