函数

function array_value_sum()
{
    $res = array();
    foreach (func_get_args() as $arr) {
        foreach ($arr as $k => $v){
            if (!isset($res[$k])){
                $res[$k] = $v;
            }else{
                $res[$k] += $v;
            }
        }
    }
    return $res;
}

实例：

$arr1 = array(311=>1, 312=>2, 314=>2);
$arr2 = array(311=>2, 312=>2, 313=>5, 314=>9);
$arr3 = array(314=>10);
$newArr = array_value_sum($arr1, $arr2, $arr3);
print_r($newArr);

输出：

Array ( [311] => 3 [312] => 4 [314] => 21 [313] => 5 )