PHP array traversal foreach ($arr as &$value) usage introduction

This article introduces how to use foreach loop to traverse arrays in PHP. Friends in need can refer to it.

Starting from php5, you can add & before $value to modify the elements of the array. This method will assign a value by reference instead of copying a value, which reduces the waste of space and is a good method.

Example:

<?php
$arr = array(1, 2, 3, 4);
foreach ($arr as &$value) {
    $value = $value * 2;
}
// $arr is now array(2, 4, 6, 8)
?>

This method is only available when the array being traversed can be referenced (for example, it is a variable).

Example:

<?php
foreach (array(1, 2, 3, 4) as &$value) {
    $value = $value * 2;
}
?>

Detailed reference: http://bbs.it-home.org/shouce/php5/control-structures.foreach.html