เปรียบเทียบความเร็วการทำงานระหว่าง for กับ foreach By DS_Ohm

<?php
/**
 * DS Timer v2.0.0
 * 
 * @name Timer Class
 * @version 2.0.0
 * @author Narong Rammanee, <ranarong@live.com>
 * @copyright Copyright (c) 2010, Narong Rammanee
 * @license No Licence Free 2010
 */
class Timer {
	private $elapsedTime;
	private $unitTime;

	/**
	 * Start Timer
	 * 
	 * @return void
	 */ 
	public function start() {
		
		if(!$this->elapsedTime = $this->getMicrotime())
			throw new Exception('Error obtaining start time!');
	}

	/**
	 * Stop Timer
	 * 
	 * @return stop time
	 */ 
	public function stop() {
		
		if(!$this->elapsedTime = (round($this->getMicrotime() - $this->elapsedTime, 6) * 1000000))
				throw new Exception('Error obtaining stop time!');
				
		$this->unitTime = self::setUnitTime();
		
		return $this->elapsedTime.$this->unitTime;
	}

	/**
	 * define private 'getMicrotime()' method
	 * 
	 * @return micro second time
	 */ 
	private function getMicrotime() {
		
		list($useg, $seg) = explode(' ', microtime());
		return ((float)$useg + (float)$seg);
	}
	
	/**
	 * define private 'setUnitTime()' method
	 * 
	 * @return time unit 
	 */
	private function setUnitTime() {
		
		if($this->elapsedTime < 1000) {
			$this->unitTime	= '&micro;s';		
		}
		else if($this->elapsedTime >= 1000 && $this->elapsedTime < 1000000) {
			$this->elapsedTime /=  1000;
			$this->unitTime = 'ms';
		}
		else if($this->elapsedTime >= 1000000) {
			$this->elapsedTime /=  1000000;
			$this->unitTime = 's';
		}
		return $this->unitTime;
	}
?>

<style type="text/css">
	body { font:13px Tahoma, Geneva, sans-serif; }
	.txt-red { color:red; }
</style>
<?php
	require_once('class/class_timer.php');
	
	# assign array $val
	$val = range(0, 100);
	
	# assign array $value
	$value = range(0, 100);
	
	# create timer instance
	$t = new Timer;
	
	# for loop start time
	$t->start();
	
	for( $i = 0 ; $i < count($val) ; $i++ )
		for ($j = 0; $j < count($value); $j++) { }
	# for loop used time
	$tt = $t->stop();
	
	# show for loop used time
	echo 'for loop used time : <span class="txt-red">'.$tt.'</span><br />';
	
	# foreach start time 
	$t->start();
	foreach ( $val as $name ) 
		foreach ( $value as $name ) { }
	# foreach used time
	$tt = $t->stop();
	
	# show foreach loop used time
	echo 'foreach loop used time : <span class="txt-red">'.$tt.'</span><br />';
?>