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List:       php-doc-cvs
Subject:    [DOC-CVS] =?utf-8?q?svn:_/phpdoc/en/trunk/language/control-structures/_foreach.xml?=
From:       Christoph_Michael_Becker <cmb () php ! net>
Date:       2016-05-31 16:55:09
Message-ID: svn-cmb-1464713709-339246-1360844399 () svn ! php ! net
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cmb                                      Tue, 31 May 2016 16:55:09 +0000

Revision: http://svn.php.net/viewvc?view=revision&revision=339246

Log:
fix #71458: foreach docs should expand upon the references warning

Bug: https://bugs.php.net/71458 (Open) foreach docs should expand upon the references warning
      
Changed paths:
    U   phpdoc/en/trunk/language/control-structures/foreach.xml

Modified: phpdoc/en/trunk/language/control-structures/foreach.xml
===================================================================
--- phpdoc/en/trunk/language/control-structures/foreach.xml	2016-05-30 17:51:21 UTC (rev 339245)
+++ phpdoc/en/trunk/language/control-structures/foreach.xml	2016-05-31 16:55:09 UTC (rev 339246)
@@ -73,6 +73,42 @@
    </programlisting>
   </informalexample>
  </para>
+ <warning>
+  <para>
+   Reference of a <literal>$value</literal> and the last array element
+   remain even after the <literal>foreach</literal> loop. It is recommended
+   to destroy it by <function>unset</function>.
+   Otherwise you will experience the following behavior:
+  </para>
+  <informalexample>
+   <programlisting role="php">
+<![CDATA[
+<?php
+$arr = array(1, 2, 3, 4);
+foreach ($arr as &$value) {
+    $value = $value * 2;
+}
+// $arr is now array(2, 4, 6, 8)
+
+// without an unset($value), $value is still a reference to the last item: $arr[3]
+
+foreach ($arr as $key => $value) {
+    // $arr[3] will be updated with each value from $arr...
+    echo "{$key} => {$value} ";
+    print_r($arr);
+}
+// ...until ultimately the second-to-last value is copied onto the last value
+
+// output:
+// 0 => 2 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 2 )
+// 1 => 4 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 4 )
+// 2 => 6 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 6 )
+// 3 => 6 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 6 )
+?>
+]]>
+   </programlisting>
+  </informalexample>
+ </warning>
  <para>
   Referencing <literal>$value</literal> is only possible if the iterated array can be
   referenced (i.e. if it is a variable). The following code won't work:
@@ -88,13 +124,6 @@
    </programlisting>
   </informalexample>
  </para>
- <warning>
-  <para>
-   Reference of a <literal>$value</literal> and the last array element
-   remain even after the <literal>foreach</literal> loop. It is recommended
-   to destroy it by <function>unset</function>.
-  </para>
- </warning>
  <para>
   <note>
    <para>



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