更改多维数组php的值

Question

Its my first time working with multidimensional arrays in php. I need to change the second number in each sub array.

What I want is to check if the Id in the array matches the Id from the database. When the two match I want to change the 2nd entry in the sub array by adding a number to it. If the Id from the query does not match anything in the list I want a new sub array to be pushed to the end of the array with the values of Id and points_description.

Also, if its helpful, my program right now does find the matches. The only thing is, it does not update the 2D array.

$array = array(array());
while ($row_description = mysqli_fetch_array($query_description)) {
    $check = 1;
    $is_match = 0;

    foreach ($array as $i) {    
        foreach ($i as $value) {  
            if ($check == 1) {
                if ($row_description['Id'] == $value) {
                    //$array[$i] += $points_description;
                    $is_match = 1;
                }
             }

            $check++;
            $check %= 2; //toggle between check and points
        }
    }

    if ($is_match == 0) {
        array_push($array, array($row_description['Id'], $points_description));
    }
}

I feel like Im doing this so wrong. I just want to go through my 2D array and change every second value. The expected output should be a print out of all the Ids and their corresponding point value I hope this is helpful enough.

Example: $row_description['Id'] = 2 and $array = array(array(2,1), array(5,1) , array(6,1))

output should be $array = array(array(2,4), array(5,1) , array(6,1))

if $row_description['Id'] = 3 and $array = array(array(2,1), array(5,1) , array(6,1))

output should be $array = array(array(2,4), array(5,1) , array(6,1),array(3,3))

Answer 1

By default PHP will copy an array when you use it in a foreach. To prevent PHP from creating this copy you need to use to reference the value with &

Simple example :

<?php

$arrFoo = [1, 2, 3, 4, 5,];
$arrBar = [3, 6, 9,];

Default PHP behavior : Make a copy

foreach($arrFoo as $value_foo) {
    foreach($arrBar as $value_bar) {
        $value_foo *= $value_bar;
    }   
}


var_dump($arrFoo);
/* Output :
array(5) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
  [3]=>
  int(4)
  [4]=>
  int(5)

}
*/

ByReference : Don't create the copy :

foreach($arrFoo as &$value_foo) {
    foreach($arrBar as $value_bar) {
        $value_foo *= $value_bar;
    }   
}

var_dump($arrFoo);
/* Output :
array(5) {
  [0]=>
  int(162)
  [1]=>
  int(324)
  [2]=>
  int(486)
  [3]=>
  int(648)
  [4]=>
  &int(810)
}

*/