In PHP, how do you change the key of an array element?

Question

I have an associative array in the form key => value where key is a numerical value, however it is not a sequential numerical value. The key is actually an I

Answer 1

There is an alternative way to change the key of an array element when working with a full array - without changing the order of the array. It's simply to copy the array into a new array.

For instance, I was working with a mixed, multi-dimensional array that contained indexed and associative keys - and I wanted to replace the integer keys with their values, without breaking the order.

I did so by switching key/value for all numeric array entries - here: ['0'=>'foo']. Note that the order is intact.

'alfa',
    'baz'=>['a'=>'hello', 'b'=>'world'],
];

foreach($arr as $k=>$v) {
    $kk = is_numeric($k) ? $v : $k;
    $vv = is_numeric($k) ? null : $v;
    $arr2[$kk] = $vv;
}

print_r($arr2);

Output:

Array (
    [foo] => 
    [bar] => alfa
    [baz] => Array (
            [a] => hello
            [b] => world
        )
)