Bug #69725 [Opn->Nab]: foreach do not iterate all elements of an array in recursive function

Edit report at https://bugs.php.net/bug.php?id=69725&edit=1 ID: 69725 Updated by: requinix@php.net Reported by: dp dot maxime at gmail dot com Summary: foreach do not iterate all elements of an array in recursive function -Status: Open +Status: Not a bug Type: Bug Package: Scripting Engine problem Operating System: Ubuntu 15.04 PHP Version: 5.6.9 Block user comment: N Private report: N New Comment: References. The explanation for why you get exactly those results is a bit complicated, I'll explain if you need it, but the short version is that $value is a reference to the last element in $A so when you set $value=$value+1 in the second foreach you'll also update $A which in turn also affects $X and $B in the recursive calls. unset($value) after the first loop to destroy the variable and the reference, then do it after the second loop too so you learn to do that out of habit. Previous Comments: ------------------------------------------------------------------------ [2015-05-29 06:36:15] dp dot maxime at gmail dot com Description: ------------ foreach construct do not iterate all elements of an array in recursive functions. I am using PHP 5.6.9 from ppa:ondrej/php5-5.6 on Ubuntu 15.04. The version 5.6.4 from the standard Ubuntu 15.04 distribution is also affected. Test script: --------------- <?php function R(&$X, $level) { print "$level X: " . json_encode($X) . "\n"; $A = $X; foreach($A as &$value) { $value = $value - 1; } print "$level A: " . json_encode($A) . "\n"; $B = $X; foreach($B as &$value) { $value = $value + 1; } print "$level B: " . json_encode($B) . "\n"; if ($level < 3) { R($B, $level + 1); } } $X = array(1, 2, 3); R($X, 0); Expected result: ---------------- 0 X: [1,2,3] 0 A: [0,1,2] 0 B: [2,3,4] 1 X: [2,3,4] 1 A: [1,2,3] 1 B: [3,4,5] 2 X: [3,4,5] 2 A: [2,3,4] 2 B: [4,5,6] 3 X: [4,5,6] 3 A: [3,4,5] 3 B: [5,6,7] Actual result: -------------- 0 X: [1,2,3] 0 A: [0,1,2] 0 B: [2,3,4] 1 X: [2,3,4] 1 A: [1,2,3] 1 B: [3,4,4] 2 X: [3,4,4] 2 A: [2,3,3] 2 B: [4,5,4] 3 X: [4,5,4] 3 A: [3,4,3] 3 B: [5,6,4] ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=69725&edit=1