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PHP

Fastest way to traverse an associative array

PHP has array_walk() which can be used to traverse an array and modify it in place. I wanted to find out if array_walk() would be faster than a loop written in PHP (for, foreach). I mean, PHP’s code is written in C/C++ and traversing anything has to be faster in C than in PHP.

So, I wrote a script to traverse an array of about 100,000 elements. Below are the results (formatted for better readability):

new-host-2:exp moz$ php for.php
Method          Time taken to traverse 100,000 elements
========================================================
for		0.030004024505615
foreach		0.0066280364990234
array_walk	0.019280910491943

new-host-2:exp moz$ php for.php
Method          Time taken to traverse 100,000 elements
========================================================
for		0.041378974914551
foreach		0.0075538158416748
array_walk	0.02002215385437

new-host-2:exp moz$ php for.php
Method          Time taken to traverse 100,000 elements
========================================================
for		0.029618978500366
foreach		0.0064899921417236
array_walk	0.018718957901001

new-host-2:exp moz$ php for.php
Method          Time taken to traverse 100,000 elements
========================================================
for		0.041105985641479
foreach		0.007500171661377
array_walk	0.020205974578857

foreach traverses an associative array faster than array_walk() and for loop. In fact, it was much faster than both. I had expected array_walk to be faster but I was wrong. You will notice that the while loop isnt in there. I figured that a while loop would take about the same time as a for loop. Here is the script I ran for my experiment:

 $val) {
	$tmp = $val;
}
Timer::stop();
Timer::diff('foreach');



Timer::start();
array_walk($assocArray, function ($item, $key) {
	$tmp = $item;	

});


Timer::stop();
Timer::diff('array_walk');







class Timer
{
	protected static $start;
	protected static $stop;

	public static function start()
	{
		self::$start = microtime(true);
	}

	public static function stop()
	{
		self::$stop = microtime(true);
	}

	public static function diff($label)
	{
		print $label . "\t\t" . (self::$stop - self::$start) . PHP_EOL;
	}
}






By Moazzam

Moazzam is a software developer working in the big apple. He has over a decade of experience in development. While most of his work involves developing web applications, he does development for Android and Windows Mobile in his spare time.

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