<?php

$values = array(1,2,3);
foreach ($values as &$value) {
   $value += 1;
}
print_r($values);
foreach ($values as $index=>$value) {
   echo "{$index},{$value}\n";
}

## output
Array
(
    [0] => 2
    [1] => 3
    [2] => 4
)

0,2
1,3
2,3