将单个键值对添加到Array

Question

if (!array_key_exists('ip', $value)) {
    array_unshift($value, ['ip' => ""]);
}

.. this appends a new array, but I just need a key-value pair, like so:

Array
(
    [ip] => 192.168.1.1
    [firstname] => John
    [lastname] => Appleseed
)

Answer 1

How about:

$value = array ('foo' => 'bar');
if (! array_key_exists('baz', $value)) {
    $value = array ('baz' => 'quux') + $value;
}
var_dump($value);

See it in action.