In general, ++ is the same thing as +1. Why ++ != +1 on this code?

I used foreach, &, ++, +1.

In general, ++ is the same thing as +1.
but ++ != +1 on this code(php7.3.4), why?

$data1 = $data2 = [
    ['id' => 0],
    ['id' => 1],
    ['id' => 2],
];
foreach ($data1 as $key => &$val) {
    $val['id'] = $val['id']++;
}
foreach ($data2 as $key => &$val) {
    $val['id'] = $val['id']+1;
}

var_dump($data1 == $data2); // false. why?

thank Nigel Ren

I change this code

foreach ($data1 as $key => &$val) {
    // $val['id'] = $val['id']++;
    $val['id']++;
}

the result is true.
but i don’t know why $val['id'] = $val['id']++ != $val['id']++?

>Solution :

There is a basic difference between $i++ and ++$i.

pre-increment

++$i is Pre-increment, Increments $i by one, then returns $i

post-increment

$i++ is Post-increment, Returns $i, then increments $i by one

Addition

$i += 1 is Addition, adds 1, then return $i

Please have a look: https://www.php.net/manual/en/language.operators.increment.php

In your case use

$val['id']++; 

instead of

$val['id'] = $val['id']++;

Hope, it helps.