Pass object association by reference via & to save resources

Not really a big deal, but could save resources on larger arrays. Is also a clean code practice to avoid awkward traversing array and assigning to ‘itself’ from what is essentially a sub routine.

Does it really matter? Likely not. Using the below script on my 2.66 Core i7 with 8gigs of ram passing by reference is roughly 3-4 times faster. At 100000 array key value pairs the difference is still in microseconds (less than half a millisecond).

More information here: http://php.net/manual/en/language.references.pass.php

<?php
 
// want to loop over an array
$an_array = array();
 
// lets populate it with random values
for ($i=0; $i < 100000; $i++) { 
    $an_array[$i] = md5(uniqid(uniqid("",true),true));
}
 
// start
var_dump(microtime(true));
 
// now lets maniuplate the 'old' way
foreach ($an_array as $key => $value) {
    // this modifies the value at the index using the array and key
    $an_array[$key] = "ref original array and key";
}
 
var_dump(microtime(true));
 
// lets do it the 'new' way, notice we are passing &
foreach ($an_array as $key => &$value) {
    // $value is a reference to the $an_array[$key]
    $value = "changes source array";
}
// finish
var_dump(microtime(true));
 
?>

Sample Executions

Object	Pass reference
445	123
455	122
443	122
452	119
446	129

*Note* times in microseconds

Significant Revisions

May 6th, 2024 Converted to jekyll markdown format and copied to personal site
Jun 15th, 2011 Originally published on txcowboycoder wordpress site¹

Footnotes

Initial md Generated using https://github.com/jsr6720/wordpress-html-scraper-to-md

Original Wordpress categories: [‘PHP’]

Original Wordpress tags: “PHP”, “association”, “clean code”, “php”, “resource management”, “traverse array” ↩