Quick PHP Tip: passing by reference creates array keys

👉 Whoa! Please note that this post is 13 years old. The views expressed within might have become outdated.

Another little PHP tip that could save you a couple of debugging hours.

Consider the following code, and notice I use the ampersand character to fetch the value by reference:

<?php $a = array('a' =?> 1, 'b' => 2);
	$c = &$a['c'];

Shockingly, this won't give you a notice or warning. Instead, it'll output this array:

   [a] => 1
   [b] => 2
   [c] =>

This might have disastrous results, if your code works with those array keys one way or another. So be warned, and learn to love functions such as array_key_exists and empty.