PHP：从嵌套关联数组中查找动态元素

Question

I'm working on a function that looks like this:

public function myfunction($mainArr, $keys) {
    // $mainArr: a nested associative array
    // $keys: a simple array of strings, example: array('string_1', 'string_2', 'string_3')
    $totalKeys = count(keys);
    if(totalKeys == 1) {
        return mainArr[keys[0]];
    } else if(totalKeys == 2) {
        return mainArr[keys[0]][keys[1]];
    } else if(totalKeys == 3) {
        return mainArr[keys[0]][keys[1]][keys[2]];
    } else if(totalKeys == 4) {
        return mainArr[keys[0]][keys[1]][keys[2]][keys[3]];
    } else if(totalKeys == 5) {
        return mainArr[keys[0]][keys[1]][keys[2]][keys[3]][keys[4]];
    }
    // the same pattern continues..
}

I want to change this function into something more dynamic rather than a big list of "if" conditions, is it possible somehow?

Answer 1

You can do it for example this way:

function get_value(array $source, array $keys) {
    foreach ($keys as $key) {
        if (isset($source[$key])) {
            $source = $source[$key];
        }
        else {
            return null;
        }
    }

    return $source;
}

If $keys describes an invalid path inside $source then null will be returned.