PHP foreach without reference misses elements

Question

I tend to find that when using foreach stuctures without using references, some elements of the array are missing.

$array = array();

/* ... */

$array[] = 1;
$array[] = 2;
$array[] = 3;

/* ... */

print_r($array); /* print_r always shows all elements */

foreach ($array as $element) { /* missing elements */ }
foreach ($array as &$element) { /* does a fine job */ }

I have had three independent occurrences of this in my code. The fix is easy (add &), but it sounds like a bug either in PHP or in my setup...

Are more people experiencing this? What is the problem?

PHP 5.4.12

EDIT

Case:

$a = array();
$a[] = 1;
$a[] = 2;
$a[] = 3;

foreach ($a as &$e)
{
    echo $e;
}

echo '<br>';

foreach ($a as $e)
{
    echo $e;
}

Output:

123
122

I dont think so man... are you expecting element to start at 1 instead of 0? — Seth McClaine, Oct 05 '13 at 22:45
what about showing us what is currently executed in the foreach? — bwoebi, Oct 05 '13 at 22:47
Could you please create an exact example which shows the problem? — Lajos Veres, Oct 05 '13 at 22:48
Your test code produces "Parse error: syntax error, unexpected '[' in php shell code on line 1" because it should be $a=array(); — JAL, Oct 05 '13 at 23:01
Other than that... Runs as you say. Maybe someone has a good explanation, I don't yet. — JAL, Oct 05 '13 at 23:02
possible duplicate of [PHP Pass by reference in foreach](http://stackoverflow.com/questions/3307409/php-pass-by-reference-in-foreach) — Mark Baker, Oct 05 '13 at 23:10
There's a reason why the [PHP manual](http://www.php.net/manual/en/control-structures.foreach.php) warns about using by reference in a foreach loop — Mark Baker, Oct 05 '13 at 23:11
See http://stackoverflow.com/questions/4969243/strange-behavior-of-foreach/4969286#4969286 for a full explanation of exactly what's happening — Mark Baker, Oct 05 '13 at 23:14

score 0 · Answer 1 · edited Oct 06 '13 at 00:27

0

Just confirmed.

<?php
  $x[]=1;
  $x[]=2;
  $x[]=3;
  $x[]=4;
  foreach($x as $y) {
    var_dump($y);
  }
?>

int(1) int(2) int(3) int(4)

edited Oct 06 '13 at 00:27

nickb

59,313
13
108
143

answered Oct 05 '13 at 22:52

Seth McClaine

9,142
6
38
64

I figured out when the oddity is reproduced, please try again! – Taco de Wolff Oct 05 '13 at 23:00

score 0 · Answer 2 · answered Aug 01 '15 at 21:19

It seems that this issue is solved in PHP ver. 5.6.10.

I have an array with 8 elements. Here is the var_dump:

array(8) { [0]=> string(18) "lname is required." [1]=> string(18) "fname is required." [2]=> string(18) "email is required." [3]=> string(22) "password1 is required." [4]=> string(22) "password2 is required." [5]=> string(44) "First Name must be letters and numbers only." [6]=> string(43) "Last Name must be letters and numbers only." [7]=> string(22) "Invalid e-mail address" }

I print out the array using this code:

foreach ($_SESSION['error'] as $error) { print $error . "
\n"; }

My MAMP localhost uses PHP ver. 5.6.10 and the result is perfect:

"lname is required. fname is required. email is required. password1 is required. password2 is required. First Name must be letters and numbers only. Last Name must be letters and numbers only. Invalid e-mail address"

My remote server uses PHP ver. 5.3 and in this case the server prints only the first element:

"lname is required."

When I changed the code as Taco suggested (foreach ($_SESSION['error'] as &$error)) the ver. 5.3. also gave the good (and expected) result.

PHP foreach without reference misses elements

2 Answers2