I have a multi-dimensional array that I need to extract data from. Given a string in the format of "person.first" I want to descend in to the array looking for person -> first. I wrote this array_dive() function to facilitate this lookup.

function array_dive(string $needle, array $haystack) {
    // Split at the periods
    $parts = explode(".", $needle);

    // Loop through each level of the hash looking for elem
    $arr = $haystack;
    foreach ($parts as $elem) {
        //print "Diving for $elem<br />";
        $arr = $arr[$elem] ?? null;

        // If we don't find anything stop looking
        if ($arr === null) {
            break;
        }
    }

    // If we find a scalar it's the end of the line, anything else is just
    // another branch, so it doesn't cound as finding something
    if (is_scalar($arr)) {
        $ret = $arr;
    } else {
        $ret = null;
    }

    return $ret;
}

Here is a sample script that shows the function in action.