Bug #74751 [Com]: Array content changes but doesn't change

Edit report at https://bugs.php.net/bug.php?id=74751&edit=1 ID: 74751 Comment by: danack@php.net Reported by: grmnpl46 at gmail dot com Summary: Array content changes but doesn't change Status: Not a bug Type: Bug Package: Arrays related Operating System: any PHP Version: Irrelevant Block user comment: N Private report: N New Comment: grmnpl - the explanation is that $a is still a variable which is a reference to the original array. Writing values into it, will write that value into the original array. Re-using the names of variables is usually a bad idea - particularly when using them with references. The behaviour you probably expected can be achieved by explicitly unsetting the $a variable: <?php $arr = [ [1, 2], [3, 4] ]; foreach($arr as $i => &$a) { if($i === 0) { $a[0] = 6; $a[1] = 7; } } //correct result print_r($arr); foreach($arr as &$a) print_r($a); //correct result unset($a); foreach($arr as $a) print_r($a); //bug - displays same values twice ?> This example shows that writing any variable into $a will alter the original array. <?php $arr = [ [1, 2], [3, 4] ]; foreach($arr as $i => &$a) { if($i === 0) { $a[0] = 6; $a[1] = 7; } } $a = "Wooo, magic"; foreach($arr as $b) { print_r($b); } ?> Previous Comments: ------------------------------------------------------------------------ [2017-06-13 03:35:17] requinix@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php Please read the red warning on the foreach docs page. ------------------------------------------------------------------------ [2017-06-13 03:23:56] grmnpl46 at gmail dot com Description: ------------ I'm altering only the first element of the array but the second one is somehow modified too - or the first one is displayed instead. This doesn't happen if at the second foreach I put also reference. Test script: --------------- $arr = [ [1, 2], [3, 4] ]; foreach($arr as $i => &$a) { if($i === 0) { $a[0] = 6; $a[1] = 7; } } //correct result print_r($arr); foreach($arr as &$a) print_r($a); //correct result foreach($arr as $a) print_r($a); //bug - displays same values twice Expected result: ---------------- the 2 arrays should have different values. Actual result: -------------- the 2 arrays are identical ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74751&edit=1