PHP - 添加到多维数组的值

Question

I basically want to change the value of a multidimensional array by adding to the previous value.

Example:

$arr=array(1,2,3);

foreach($arr as $val){
    $arrTotal[1][2][3]=$val;
}

This would make $arrTotal[1][2][3]=3

What I really want is $arrTotal[1][2][3]=6

3+2+1.

I have tried an approach like so:

$arrTotal[1][2][3]+=$val;

But to no avail.

Answer 1

Easiest approach:

$arr = array(1,2,3);
$arrTotal[1][2][3] = array_sum($arr);