PHP - 使用string作为键从多维数组中获取对元素的引用

Question

is there an easy, non-eval-using method for getting a reference to an element of a multidimensional array? The key should be passed as a string.

Here's an example:

getSessionReference('1.4.2', $arrReference);

should return a reference to

$_SESSION['1']['4']['2']

and so a call like

$arrReference['foo'] = 'bar';

would change it to

$_SESSION['1']['4']['2']['foo'] = 'bar'

Any ideas?

Thanks in advance.

Answer 1

$arr[5][6][7] = 111;

$cursor =& $arr;
foreach (explode('.', '5.6') as $key) {
    $cursor =& $cursor[$key];
}

var_dump($arr);
var_dump($cursor);
$cursor['foo'] = 5;
var_dump($arr);
var_dump($cursor);

http://codepad.viper-7.com/XUEhMj

or in function form

function & getSessionRef($keyPath) {
    $cursor =& $_SESSION;
    foreach (explode('.', $keyPath) as $key) {
        $cursor =& $cursor[$key];
    }
    return $cursor;
}

$cursor =& getSessionRef('a.6');

btw - I used the php feature named references in that code, where you see the ampersand like =& .

Answer 2

Use pass-by-reference.

function getReference($key, &$arr)
{
    $e = explode('.', $key);
    foreach ($_SESSION[$e[0]][$e[1]][$e[2]] as $k => &$v)
        $arr[$k] = $v;
}

$arr = array();
getReference("1.4.2", $arr);

ps: this does not actually return the reference but it serves your needs.