PHP, Merging arrays with common keys

Solution 1:

function merge_common_keys(){
    $arr = func_get_args();
    $num = func_num_args();

    $keys = array();
    $i = 0;
    for ($i=0; $i<$num; ++$i){
        $keys = array_merge($keys, array_keys($arr[$i]));
    }
    $keys = array_unique($keys);

    $merged = array();

    foreach ($keys as $key){
        $merged[$key] = array();
        for($i=0; $i<$num; ++$i){
            $merged[$key][] = isset($arr[$i][$key]) ? $arr[$i][$key] : null;
        }
    }
    return $merged;
}

Usage:

$merged = merge_common_keys($array1,$array2);

PS. It can work with more than two arrays, just pass as many as you want as next arguments.

Solution 2:

Something like this? http://php.net/array_merge_recursive