PHP - Changing a value from a query result using foreach

Question

I have a result from a SQL query stored inside $assignmentsViewList:

Array
(

    [0] => Array
    (
        [assign_id] => 302
        [ClassCount] => 25
    )

    [1] => Array
    (
        [assign_id] => 303
        [ClassCount] => 25
    )

    [2] => Array
    (
        [assign_id] => 325
        [ClassCount] => 25
    )

)

When I use it inside a foreach to change the value of ClassCount:

foreach ($assignmentsViewList as $task) {
    $task['ClassCount'] = 2;
}

It doesn't work. But if I try this:

$assignmentsViewList[0]['ClassCount']=2;

The code works well. But I need it to work inside the foreach loop.

What exactly are you trying to achieve here? Do you want to update all the `ClassCount` values? Or just one? — Indrasis Datta, Oct 05 '16 at 05:23
Please take a look at my answer. It should solve your purpose. — Indrasis Datta, Oct 05 '16 at 05:25

score 2 · Accepted Answer · answered Oct 05 '16 at 05:23

2

In order to be able to directly modify array elements within the loop precede $task with &. In that case the value will be assigned by reference.

Reference: PHP foreach()

Try this:

foreach ($assignmentsViewList as &$task) {
    $task['ClassCount'] = 2;   /* It will overwrite all 'ClassCount' values to 2 */
}

answered Oct 05 '16 at 05:23

Indrasis Datta

8,692
2
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I have seen this '&' before, but I didn't know that this is needed when modifying. Thank you. – Vince Parker Oct 05 '16 at 05:27

score 1 · Answer 2 · edited Feb 04 '22 at 09:02

1

use & .

Its means iterated over references to actual values of array &$task

 foreach ($assignmentsViewList as &$task)
{
  $task['ClassCount'] = 2;  values of array
}

without & means its iterated over copy of array value.so its not overwrite your array.

take a look in documentation

edited Feb 04 '22 at 09:02

Glorfindel

21,988
13
81
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answered Oct 05 '16 at 05:36

JYoThI

11,977
1
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PHP - Changing a value from a query result using foreach

2 Answers2