Brian Matovu mtvbrianking

Why objects (usually) use less memory than arrays in PHP

This is just a small post in response to [this tweet][tweet] by Julien Pauli (who by the way is the release manager for PHP 5.5). In the tweet he claims that objects use more memory than arrays in PHP. Even though it can be like that, it's not true in most cases. (Note: This only applies to PHP 5.4 or newer.)

The reason why it's easy to assume that objects are larger than arrays is because objects can be seen as an array of properties and a bit of additional information (like the class it belongs to). And as array + additional info > array it obviously follows that objects are larger. The thing is that in most cases PHP can optimize the array part of it away. So how does that work?

The key here is that objects usually have a predefined set of keys, whereas arrays don't:

Laravel debug database queries

Raw SQL

SELECT
  users.name AS staff,
  facilities.name AS facility
FROM
  users

WINDOWS XAMPP VHOSTS

Enable vHosts

Uncommenting the following line in C:\xampp\apache\conf\httpd.conf

# Virtual hosts
Include conf/extra/httpd-vhosts.conf

curl -X POST \
  http://localhost:8000/api/v1/oauth/token \
  -H 'Accept: application/json' \
  -d 'grant_type=authorization_code' \
  -d 'client_id=b8e7163a-83a0-4386-b0bc-697a96edef14' \
  -d 'client_secret=bNQbpQnMPXayTn8XFPRQDWvIyyclN5pKnccVVUNx' \
  -d 'redirect_uri=http://localhost:8000/test/callback' \
  -d 'code=def502006626c316151b4f074308...'

-<?php
-/**
- * Delete files older than a given age recursively.
- *
- * @link https://www.php.net/manual/en/class.recursivedirectoryiterator.php#111142 Source
- *
- * @param  string  $dir      Path to directory having the files
- * @param  int     $age      In seconds
- * @param  string  $pattern  File name pattern

	<?php

	/**
	* Get files in directory.
	*
	* @link https://www.php.net/manual/en/class.recursivedirectoryiterator.php#111142 Source
	*
	* @param string $dir Directory path
	*
	* @throws UnexpectedValueException

-<?php
-/**
- * Delete files older than a given age.
- *
- * @param  string  $dirPath  Path to directory having the files
- * @param  int     $maxAge   In seconds
- * @param  string  $pattern  File name pattern
- *
- * @return array             Deleted files

	<?php

	header('Content-Type: application/json');

	$countries = array(
	[
	'name' => 'Afghanistan',
	'code' => 'AF'
	],
	[

	<?php

	class XMLElement extends \SimpleXMLElement
	{
	public function get($attr, $default = null)
	{
	if (empty($this->{$attr})) {
	return $default;
	}
	return $this->{$attr};

	<?php
	namespace Fry;
	use JsonStreamingParser\Listener;

	/**
	* This implementation allows to process an object at a specific level
	* when it has been fully parsed
	*/
	class ObjectListener implements Listener
	{