PHP：数组的内部指针在最后一个元素之前停止一个元素 - 很奇怪

Question

I have a simple multidimensional array. I modify it - ie. I add data to it - in a foreach loop, accessing its elements by reference:

 $array = array(
    array('id' => 12, 'name' => 'John1', 'surname' => 'Smith1'),
    array('id' => 13, 'name' => 'John2', 'surname' => 'Smith2'),
    array('id' => 14, 'name' => 'John3', 'surname' => 'Smith3'),
    array('id' => 15, 'name' => 'John4', 'surname' => 'Smith4'),
 );

 foreach($array as &$a) {
    $a['middlename'] = 'Robert';
 }

Now what's below shows that $array is perfectly in order:

print('<pre>'.print_r($array,true).'</pre>'); results in:

    Array
    (
        [0] => Array
            (
                [id] => 12
                [name] => John1
                [surname] => Smith1
                [middlename] => Robert
            )

        [1] => Array
            (
                [id] => 13
                [name] => John2
                [surname] => Smith2
                [middlename] => Robert
            )

        [2] => Array
            (
                [id] => 14
                [name] => John3
                [surname] => Smith3
                [middlename] => Robert
            )

        [3] => Array
            (
                [id] => 15
                [name] => John4
                [surname] => Smith4
                [middlename] => Robert
            )

    )

But while I loop though it, internal pointer stops right before last element:

 foreach($array as $a) {
     print('<pre>'.print_r($a['id'],true).'</pre>');
 }

outputs:

 12
 13
 14
 14

Any hints what's going on?

UPDATE: The answer I picked is correct and moreover I found this: PHP Pass by reference in foreach Thx, SO.

Answer 1

I've had a similar issue, when modifying an array with a foreach and then accessing the array afterwards. My guess is that you are not destroying the reference after you loop through, and are overwriting the value accidentally. Try unset($a); after your foreach.