access php array children through parameters?

Question

I have a unique case where I have an array like so:

$a = array('a' => array('b' => array('c' => 'woohoo!')));

I want to access values of the array in a manner like this:

• some_function($a, array('a')) which would return the array for position a
• some_function($a, array('a', 'b', 'c')) which would return the word 'woohoo'

So basically, it drills down in the array using the passed in variables in the second param and checks for the existence of that key in the result. Any ideas on some native php functions that can help do this? I'm assuming it'll need to make use of recursion. Any thoughts would be really appreciated.

Thanks.

Answer 1

$a['a'] returns the array at position a.
$a['a']['b']['c'] returns woohoo.

Won't this do?

Answer 2

Here’s a recursive implementation:

function some_function($array, $path) {
    if (!count($path)) {
        return;
    }
    $key = array_shift($path);
    if (!array_key_exists($key, $array)) {
        return;
    }
    if (count($path) > 1) {
        return some_function($array[$key], $path);
    } else {
        return $array[$key];
    }
}

And an iterative implementation:

function some_function($array, $path) {
    if (!count($path)) {
        return;
    }
    $tmp = &$array;
    foreach ($path as $key) {
        if (!array_key_exists($key, $tmp)) {
            return;
        }
        $tmp = &$tmp[$key];
    }
    return $tmp;
}

These functions will return null if the path is not valid.

Answer 3

You could try with RecursiveArrayIterator

Here is an example on how to use it.

Answer 4

This is untested but you shouldn't need recursion to handle this case:

function getValueByKey($array, $key) {
    foreach ($key as $val) {
        if (!empty($array[$val])) {
            $array = $array[$val];
        } else return false;
    }
    return $array;
}