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Php – While destructuring array data in the head of a foreach() loop, can new elements be assigned to the original input array?

Since PHP7.1, a foreach() expression can implement array destructuring as a way of unpacking row values and make individualized variable assignments for later use.

When using array destructuring within the head/signature of a foreach() loop, can new elements be declared instead of merely being accessed?

For example:

$array = [
    ['foo' => 'a', 'bar' => 1],
    ['foo' => 'b', 'bar' => 2],
];

Can I append a new element to each row of the original array with the key new?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    Yes, data can be appended to the rows of the original input array directly in the head of a foreach().

    Details:

    • The new element must be declared by reference (the value must be a variable prepended with &) -- otherwise there is no indication to modify the original array.
    • If the reference variable is not later assigned a value, the default value will be null.

    Code: (Demo)

    $array = [
    ['foo' => 'a', 'bar' => 1],
    ['foo' => 'b', 'bar' => 2],
];

foreach ($array as ['new' => &$x, 'bar' => $x]);

var_export($array);

    Output:

    array (
  0 => 
  array (
    'foo' => 'a',
    'bar' => 1,
    'new' => 1,
  ),
  1 => 
  array (
    'foo' => 'b',
    'bar' => 2,
    'new' => 2,
  ),
)

    Here is another answer that uses this technique and assigns the reference values via another loop.


  2. 0

    Try to modify the original array separately within the loop

        $array = [
        ['foo' => 'a', 'bar' => 1],
        ['foo' => 'b', 'bar' => 2],
    ];
    
    foreach ($array as &$row) {
        $row['new'] = 'your_new_value';
    }
    
    // It's important to unset the reference to $row to avoid any unexpected behavior later.
    unset($row);
    
    // Now $array has a new key 'new' in each row.
    print_r($array);
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