hassan 7snovic

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:

	<html>
	<body>
	<p>Here are Webber’s points:</p>
	<ul>
	<li>If a method can be static, declare it static. Speed improvement is by a factor of 4.</li>
	<li>echo is faster than print.(<em>* compare with list from phplens by John Lim</em>)</li>
	<li>Use echo’s multiple parameters instead of string concatenation.</li>
	<li>Set the maxvalue for your for-loops before and not in the loop.</li>
	<li>Unset your variables to free memory, especially large arrays.</li>
	<li>Avoid magic like __get, __set, __autoload</li>

	Object.prototype.join = function(glue, separator) {
	var object = this;

	if (glue == undefined)
	glue = '=';

	if (separator == undefined)
	separator = ',';

	return Object.keys(object).map(function (key, value) { return [key, value].join(glue); }).join(separator);

	./ccsmtpd[3519]: Starting thread for socket #5
	220 kwf.dyndns.org SMTP CCSMTP
	C5: EHLO mail-ey0-f180.google.com
	S5: 502 Command not implemented
	C5: HELO mail-ey0-f180.google.com
	S5: 250 Ok
	C5: MAIL FROM:<[email protected]>
	S5: 250 Ok
	C5: RCPT TO:<[email protected]>
	S5: 250 Ok

	#301 Redirects for .htaccess

	#Redirect a single page:
	Redirect 301 /pagename.php http://www.domain.com/pagename.html

	#Redirect an entire site:
	Redirect 301 / http://www.domain.com/

	#Redirect an entire site to a sub folder
	Redirect 301 / http://www.domain.com/subfolder/

	#!/bin/bash -e
	# UDF Documentation: http://www.mysqludf.org/lib_mysqludf_preg/

	yum -y install pcre-devel gcc make automake mysql-devel
	wget http://www.mysqludf.org/lib_mysqludf_preg/lib_mysqludf_preg-1.0.1.tar.gz
	tar -zxvf lib_mysqludf_preg-1.0.1.tar.gz
	cd lib_mysqludf_preg-1.0.1
	./configure
	make install
	echo "You'll need to enter your MySQL password a few times to install the UDFs and test them"