Strange foreach loop after modifying array

Question

As I wrote some code, PHP confused me a little as I didn't expected the result of the following code:

$data = array(array('test' => 'one'), array('test' => 'two'));

foreach($data as &$entry) {
    $entry['test'] .= '+';
}

foreach($data as $entry) {
    echo $entry['test']."\n";
}

I think it should output

one+
two+

However the result is: http://ideone.com/e5tCsi

one+
one+

Can anyone explain to me why?

bwoebi · Accepted Answer · 2013-05-02 16:35:29Z

3

This is expected behaviour, see also https://bugs.php.net/bug.php?id=29992.

The reference is maintained when using the second foreach, so when using the second foreach the value of $entry, which points still to $data[1], is overwritten with the first value.

P.s. (thanks to @billyonecan for saying it): you need to unset($entry) first, so that your reference is destroyed.

answered May 2, 2013 at 16:35

bwoebi

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1 Comment

billyonecan Over a year ago

+1 - Side Note: You can break the binding between the variable and content by using unset() - php.net/manual/en/language.references.unset.php

newacct · Accepted Answer · 2013-05-03 06:57:04Z

0

This is mentioned specifically in the documentation for foreach. You should unset the loop variable when it gets elements of the array by reference.

Warning

Reference of a $value and the last array element remain even after the foreach loop. It is recommended to destroy it by unset().

answered May 3, 2013 at 6:57

newacct

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