PHP - Notice: Only variables should be passed by reference

Question

Getting the following notice in PHP 7.4:

Notice: Only variables should be passed by reference

In:

$roots = array();
foreach ($data as $row) {   
    $row->type = end(explode(',',(implode(array_slice(explode ( ':',  $row->global_id), -2, 1)))));
    if ($row->parent_global_id === null) {
        $roots[]= $row;
    } else {
        $data[$row->parent_global_id]->children[] = $row;
    }
    unset($row->parent_global_id);
    unset($row->global_id);
}

at line:

$row->type = end(explode(',',(implode(array_slice(explode ( ':',  $row->global_id), -2, 1)))));

I have seen other questions on this at SO, but can't quite figure out how to fix it in this instance. Ideas?

`end` is a little weirder than other functions because it not only returns the last, it also resets the array pointer and thus requires a reference variable to act upon. The short answer is that you have to break this into a two lines, a variable assignment followed by the `end` call. — Chris Haas, Jul 15 '22 at 01:55
The sample isn't minimal (as explained in the linked article). A minimal example would consist of something like a call to `end` taking the result of an `explode`. — outis, Jul 15 '22 at 01:59
Also covered by "[Only variables should be passed by reference](https://stackoverflow.com/q/4636166/90527)". — outis, Jul 15 '22 at 02:02

score 3 · Accepted Answer · answered Jul 15 '22 at 01:56

Assign the explode output to a variable. Send the variable to the end function.

$roots = array();
foreach ($data as $row) {
    $var = explode(',',(implode(array_slice(explode ( ':',  $row->global_id), -2, 1))));
    $row->type = end($var);
    if ($row->parent_global_id === null) {
        $roots[]= $row;
    } else {
        $data[$row->parent_global_id]->children[] = $row;
    }
    unset($row->parent_global_id);
    unset($row->global_id);
}

PHP - Notice: Only variables should be passed by reference

1 Answers1