Edit report at https://bugs.php.net/bug.php?id=60534&edit=1
ID: 60534
Comment by: anon at anon dot anon
Reported by: aron dot cederholm at gmail dot com
Summary: Iterating an array twice w and w/o references
changes last item to second last
Status: Open
Type: Bug
Package: Arrays related
Operating System: Arch Linux
PHP Version: 5.3.8
Block user comment: N
Private report: N
New Comment:
This gets submitted as a bug about twice a month. It's still not a bug.
After the first loop finishes $a is a reference to the last element of the
array. That means that during the second loop, the last value of the array is
constantly being modified by the loop. Once it gets to the last element, 'd'
has been overwritten already.
foreach ($array as &$a) {
echo "($a): " . join(',', $array) . "\n";
}
foreach ($array as $a) {
echo "($a): " . join(',', $array) . "\n";
}
(a): a,b,c,d
(b): a,b,c,d
(c): a,b,c,d
(d): a,b,c,d
(a): a,b,c,a
(b): a,b,c,b
(c): a,b,c,c
(c): a,b,c,c
As it says in the manual, unset() after foreach'ing by reference:
http://www.php.net/manual/en/control-structures.foreach.php
Previous Comments:
------------------------------------------------------------------------
[2011-12-15 15:15:12] aron dot cederholm at gmail dot com
Description:
------------
Iterating an array twice, first time with references, second time *without*
references, will trigger a bug in the second iteration where the last item of
the
array is overwritten by the second last item in the array. This seem to be the
same bug as #46123, which was dismissed on erroneous grounds
Test script:
---------------
<?
# For a more verbose look at this bug, watch http://pastebin.com/gq2qekYh
$array = array('a', 'b', 'c', 'd'); # testing array
foreach ($array as &$a) {}
foreach ($array as $a) {}
echo join(',', $array); # will produce a,b,c,c *not* a,b,c,d as expected
die();
## while, these will work as expected
# 1
foreach ($array as $a) {}
print_r($array);
die();
# 2
foreach ($array as &$a) {}
print_r($array);
die();
# 3
foreach ($array as &$a) {}
foreach ($array as &$a) {}
print_r($array);
die();
# 4
foreach ($array as $a) {}
foreach ($array as $a) {}
print_r($array);
die();
# 5
foreach ($array as $a) {}
foreach ($array as &$a) {}
print_r($array);
die();
?>
Expected result:
----------------
a,b,c,d
Actual result:
--------------
a,b,c,c
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=60534&edit=1
