Doc #71458 [NEW]: foreach docs should expand upon the references warning

From: requinix@php.net Operating system: PHP version: Irrelevant Package: Scripting Engine problem Bug Type: Documentation Problem Bug description:foreach docs should expand upon the references warning Description: ------------ Every other month there's a bug report about how having two foreach loops, the first with a reference and the second without, results in unexpected behavior. (The bug system suggested four of them to me now as possible duplicates of this.) While there is a warning in the documentation, "Warning Reference of a $value and the last array element remain even after the foreach loop. It is recommended to destroy it by unset()." an example would be helpful to illustrate what the effects of that can look like to a developer. Plus it would make the warning box larger and more visible. An example such as: Test script: --------------- <?php $array = [1, 2, 3, 4, 5]; foreach ($array as &$n) { // $n is a reference to an item in $array $n = $n * 2; } // $array == [2, 4, 6, 8, 10] // without an unset($n), $n is still a reference to the last item: $array[4] foreach ($array as $k => $n) { // $array[4] will be updated with each value from $array... echo "{$k} => {$n} "; print_r($array); } // ...until ultimately the second-to-last value is copied onto the last value // output: // 0 => 2 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 8, [4] => 2 ) // 1 => 4 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 8, [4] => 4 ) // 2 => 6 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 8, [4] => 6 ) // 3 => 8 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 8, [4] => 8 ) // 4 => 8 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 8, [4] => 8 ) ?> -- Edit bug report at https://bugs.php.net/bug.php?id=71458&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=71458&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=71458&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=71458&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=71458&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=71458&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=71458&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=71458&r=needscript Try newer version: https://bugs.php.net/fix.php?id=71458&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=71458&r=support Expected behavior: https://bugs.php.net/fix.php?id=71458&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=71458&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=71458&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=71458&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=71458&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=71458&r=dst IIS Stability: https://bugs.php.net/fix.php?id=71458&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=71458&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=71458&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=71458&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=71458&r=mysqlcfg