PHP技术问询：如何通过数组位置引用修改原变量值？

Hey there! Let's break down why your original code isn't working and how to fix it.

Why your current code doesn't change $x #

When you assign $x and $y to the array like array($x, $y), PHP creates copies of those variables' values and stores them in the array. So $arr[0] is just a duplicate of $x's original value, not linked to the actual $x variable. Changing the array element only modifies that copy, leaving $x untouched.

How to modify $x via the array (using references) #

To make the array element point directly to the original $x variable (instead of a copy), you need to use the reference operator & when adding the variable to the array. Here's the adjusted code:

$x = 'hello world';
$y = 'bye world';
// Use & to store references to $x and $y in the array
$arr = array(&$x, &$y);
$arr[0] = 'new string';
var_dump($x); // Output: string(10) "new string"

What's happening here? #

• The & tells PHP: "Don't copy the value of $x into the array—instead, make this array element a pointer to the same memory location where $x is stored."
• When you update $arr[0], you're writing directly to that shared memory space, so $x automatically reflects the change.

A quick note #

This works in PHP 5 and later. If you ever need to break the link between the array element and the original variable later, you can use unset($arr[0])—this removes the reference without affecting the original $x value.

内容的提问来源于stack exchange，提问作者Angel Esc