Bug #63179 [Dup]: foreach: Using variable reference leads to inconsistent data

Edit report at https://bugs.php.net/bug.php?id=63179&edit=1 ID: 63179 Updated by: nikic@php.net Reported by: uli dot staerk at globalways dot net Summary: foreach: Using variable reference leads to inconsistent data Status: Duplicate Type: Bug Package: Scripting Engine problem Operating System: Linux PHP Version: Irrelevant Block user comment: N Private report: N New Comment: @uli: Maybe it would help you to understand the behavior if you wrote those two foreach loops out. Your code is roughly equivalent to the following: <?php // first loop $value =& $testdata[0]; $value =& $testdata[1]; // second loop $value = $testdata[0]; $value = $testdata[1]; So after the second loop $value is a reference to $testdata[1]. You could say that those two variables are synonyms. So when in the second loop you assign to $value again it is still a reference to $testdata[1]. So if you change $value, then $testdata[1] is changed too. Personally I think that we should break the reference after the foreach loop, simply to avoid the WTF moment here. I just wanted to explain why the current behavior is consistent ;) Previous Comments: ------------------------------------------------------------------------ [2012-09-29 09:38:22] uli dot staerk at globalways dot net The manual says: "On each iteration, the value of the current element is assigned to $value". This is not correct if you have a look at my example. The manual claims that an assignment happens, but the reference has some magic override here. Either you must fix this "consistent" implementation, or you have to fix the documentation like "it will not be correctly assigned if $value is a reference". ------------------------------------------------------------------------ [2012-09-29 02:52:29] laruence@php.net dup to #50485 ------------------------------------------------------------------------ [2012-09-28 21:26:52] notzippy at gmail dot com A variable that is the target of a foreach should be intrinsically unset and not need a manual process to do it. ------------------------------------------------------------------------ [2012-09-28 15:16:44] uli dot staerk at globalways dot net Description: ------------ As you can see from the example, php seems to mix up variables if you use the reference in a foreach. Despite the report bug 43806, I still think this is a bug. The variable must be set when calling foreach and must not be influenced by any previous code. Test script: --------------- <?php $testdata = array( 0 => array('foo' => 'foo'), 1 => array('bar' => 'bar') ); foreach($testdata as &$value) {} foreach($testdata as $key => $value) { if($key == 1) { print_r($value); } } Expected result: ---------------- Array ( [bar] => bar ) Actual result: -------------- Array ( [foo] => foo ) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=63179&edit=1