在php中求和两个数组值

我有两个cookie,它们的值如下：

foreach($_COOKIE as $key=>$val) {
    $piece = explode(",", $val);
    $t_cost = array($piece[3]);
    print_r($t_cost); //It prints Array ( [0] => 11 ) Array ( [0] => 11 )
    echo $total_cost = array_sum($t_cost);
}

但它只打印一个值.如何将两个值相加以求它们？

解决方法:

我认为你不需要array_sum,只需使用=运算符就可以节省一些内存

$t_cost = 0;
foreach($_COOKIE as $key=>$val) {
    $piece = explode(",", $val);
    $t_cost += $piece[3];
}
echo $t_cost;