#39011 [Opn]: foreach($_GET as $key => &$value) causes later bugs passing $_GET as a paramete

ID: 39011 User updated by: php_bug dot email at email dot digiways dot com Reported By: php_bug dot email at email dot digiways dot com Status: Open Bug Type: Arrays related Operating System: Windows XP PHP Version: 5.1.6 New Comment: Documentation describes that parameters are passed to functions by value by default. And since the behaviour you are talking about is not documented anywhere, it is definitely a bug. So, I suggest you read PHP documentation starting with http://www.php.net/manual/en/functions.arguments.php which clearly states: === By default, function arguments are passed by value (so that if you change the value of the argument within the function, it does not get changed outside of the function). If you wish to allow a function to modify its arguments, you must pass them by reference. === and then explain it again why the problem described above is not a bug although it does not do what PHP documentation states it does. Previous Comments: ------------------------------------------------------------------------ [2006-10-01 22:34:35] judas dot iscariote at gmail dot com again, THIS IS NOT A BUG ¡! but yes,this behaviuor should be described in the documentation I think. I still think this kind of code should raise an E_WARNING or something ( the idea was proposed a while ago, but refused) ------------------------------------------------------------------------ [2006-10-01 22:12:20] plyrvt at mail dot ru This bug can be described shortly: "Existance of a reference to the element of an array prevents this element to be passed by value as long as any reference point to it" ------------------------------------------------------------------------ [2006-10-01 22:02:06] php_bug dot email at email dot digiways dot com Actually this is not just about foreach, this is the generic problem with references. Apparently if you have a reference to an array element, then when you pass that array to a function and modify that element in the function, then the external array is modified as well, and not just the copy passed to the function. A small example which shows the problem: $myarray = array( 'mykey' => 'foo' ); function doit($tmp) { $tmp['mykey'] = 'bar'; } $value = &$myarray['mykey']; echo $myarray['mykey']."\n"; doit($myarray); echo $myarray['mykey']."\n"; Once again - can anyone point to the documentation page which explains this behaviour ? ------------------------------------------------------------------------ [2006-10-01 21:55:23] plyrvt at mail dot ru If you add unset($val) after foreach, original array starts back to work as expected: <?php $a['b']='foo'; function boo($_params){ $_params['b'] = 'bar'; echo $_params['b']; } foreach($a as $key => &$val) {} unset($val); echo $a['b']; boo($a); echo $a['b']; /* foo bar foo */ ?> ------------------------------------------------------------------------ [2006-10-01 21:39:58] plyrvt at mail dot ru Confirm with 5.1.6: <?php $a['b']='foo'; function boo($_params){ $_params['b'] = 'bar'; echo $a['b']; } foreach($a as $key => &$val) {} // ?! echo $a['b']; boo($a); echo $a['b']; ?> If you comment out foreach loop or remove & near $val, code works OK. Loop does nothing and $val is *never* mentioned in code elsewhere. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/39011 -- Edit this bug report at http://bugs.php.net/?id=39011&edit=1