Php, problem with increasing key value by 1 - php

Question

I have spent now 2 days figuring out this problem. I'm trying to create voting script which reads .txt file and modifies values inside it. I have problem with foreach part where I try to add +1 in votes of person. 1-5 is id of person, number after | is amount of votes. First output is:
Array
(
[0] => 1|2
[1] => 2|6
[2] => 3|8
[3] => 4|3
[4] => 5|10
and I want it to add just +1 in last number. But if I try to use increment, I get error: "PHP Fatal error: Cannot increment/decrement overloaded objects nor string offsets in..."
foreach ($file_contents as &$id) {
if ($id == 2) {
$id[2]++;
}
}
print_r($file_contents);
I'm still learning PHP and this is weird to me, because just giving "$id[2] = 8" actually modifies that value. Why ++ can't be used? What's way around this?
Array
(
[0] => 1|2
[1] => 2|8
[2] => 3|8
[3] => 4|3
[4] => 5|10
)

Answer 1

Use json instead. It will make your life much easier.
Json is a text string that can be decode in to an array.
Either a indexed array or an associative array. Associative is preferred in this case in my opinion.
$votes = ["1" => 2, "2" => 6, "3" => 8, "4" => 3, "5" => 10];
// Above is an associative array with the same data as your example.
// The key is the id and the value is the votes.
// To read it from the file use:
// $votes = json_decode(file_get_contents("file.txt"));
$inputVote = 2; // someone voted on person 2.
if(!isset($votes[$inputVote])) $votes[$inputVote] = 0; // if someone voted on a person not already in the array, add the person to the array.
$votes[$inputVote]++; // increments the votes on person 2.
file_put_contents("file.txt", json_encode($votes));