PHP convert nested array to single array while concatenating keys?

Question

Here is an example array:

 $foo = array(
           \'employer\' => array(
                    \'name\' => \'Foobar Inc\',
                    \'phone\         


        

Answer 1

After a few iterations, I've been able to refine a solution to this problem that uses a stack-based approach to avoid recursion, simplifying things a bit.

/***
 * @name array_flatten
 * @author Tom Penzer @tpenzer
 * Flattens a multi-tiered array into a single-tiered 
 * associative array with keys reflective of their 
 * values' hierarchy.
 *
 * @param    array    $array       Required - the multi- 
 * level keyed array to be flattened
 * @param    string   $separator   Optional - the string 
 * used to separate the keys from different levels of 
 * the hierarchy
 *
 * @return   array    a single-level keyed array
 ***/
function array_flatten($array, $separator = '_') {
    $output = array();

    while (list($key, $value) = each($array)) {
        if (is_array($value)) {
            $build = array();
            foreach ($value as $s_key => $s_value) {
                $build[$key . $separator . $s_key] = $s_value;
            }
            unset($array[$key]);
            $array = $build + $array;
            unset($build);
            continue;//skip write to $output
        }
        $output[$key] = $value;
        unset($array[$key]);
    }

    return $output;
}

Not exactly the method requested, but it's a nice contrast to the recursive approaches to the problem.