Question

Line 3 of the code below fails if I omit the => $v portion. I get the following error:

Warning: Illegal offset type in /home/site/page.php on line 404

When the [$k] in line 5 is changed to ['$k'], i receive the following error.

Notice: Undefined index: $k in /home/site/page.php on line 404

When it is like below with the the full $k => $v everything works though. I don’t even use $v. Why do I need it in the foreach loop to make it work then?

<? if ( $arr[ 'status'][ 'chain'] ) { 
     foreach ( $arr[ 'status'][ 'chain'] as $k => $v) { ?>
        <tr>
            <td class="line_item_data status_td">
                <?= $ arr[ 'status'][ 'chain'][$k][ 'message'] ?>
            </td>
            <td align="center">
                <img src="images/green_check.gif" width="20" />
            </td>
        </tr>
    <? } 
} ?>

I did see this answer, but don’t know that it really applies. Thanks so much!

Answer 1

The construct $k => $v is used to iterate an array’s keys and values in a foreach construct. You can iterate using the values $v alone, but you cannot iterate over the keys alone $k. If you used the following:

foreach ($arr['status']['chain'] as $k)

…the foreach loop is syntactically valid but $k would be populated with the array value rather than the key. In that case, the array element $ arr[ 'status'][ 'chain'][$k][ 'message'] does not exist since $k does not hold a key valid in the array $arr['status']['chain'].

However, this can be much simpler…

Inside the loop, $v holds the array element you are attempting to index, so you merely need to access it as:

<?= $v['message'] ?>

That is the equivalent of $arr['status']['chain'][$k]['message']. So ultimately it isn’t $v that you don’t need in your loop, but rather it is $k you don’t need.

 // Iterate the values only. Keys aren't actually needed.
 foreach ( $arr[ 'status'][ 'chain'] as $v) {
     // snip html markup..
            <?= $v[ 'message'] ?>
 }