|
Rob Thompsonrob.sun3.org |
RSS ArticlesArticle Categories:
New Articles:
- More on High Resolution Security Cameras
- Bash Shell: Find Nano or Pico
- Zimbra on a VPS: Tuning
- Zimbra on a VPS: Step-by-Step
- Zimbra: It's Going Places
- Threaded Discussion Site Widget
- Scripts as Reliable Daemons
- Switch vs. If
- Zimbra
- Universities and Email Outsourcing
- High Resolution Security Cameras
- Multiple User Apache Setups
- PHP and Solaris: getcwd() Behavior
- Wapache - Win GUI Framework
- SetGID and SetUID Shell Scripts
- Multipart Mime Headers in PHP
- Parallelizing RSYNC Processes
- Oracle Tree Relationships
- PHP: Find Ophaned Files
Contact:
New comments:
- Rob (Hi Christina, Here...)
- Christina (Hello Rob, Th...)
- Mike Whitton (Hi Rob, how d...)
- Rob (Hi SpinState, I just p...)
- SpinState (Looking forward...)
- gwb (This worked fine for m...)
- Shane (I'm having a hard ti...)
- Robert (what bugs me about...)
- Josh Johnston (Micro optimi...)
- Unomi (I've done a lot of b...)
- Matt Parrott (Thank you. T...)
- ApeHanger (> case($a = 0): ...)
- Marc Gear (Don't forget tha...)
- leo (Interesting test! But...)
- Rob Thompson (Hi Phil, than...)
- Phil Davis (I've wished for...)
- Adam (I've never heard of Z...)
- open source cms (It's work...)
- open source cms (Funny prob...)
Various Scripts
Various PHP & Related ScriptsPhoto Gallery
My Photo GalleryLinks
Oracle Corporationplanet-php.net
produx.org
robsort.org
The Saab Network (TSN)
Thread Buddy
Technorati Profile
Wayne State University
muskr.at
Switch vs. If
Often, with little rhyme or reason behind it, I choose between using a switch condition or an if-else statement while coding simple condition matches in PHP. I got curious about which is actually more efficient at matching a random integer with a set of conditionals. So, I setup a script to create a set of large scripts to test the speed of these different constructs. Using the 'time' command, I measured the speed at which the condition could match a random number. Here is what I found:The switch construct is generally more than twice as fast at matching a simple integer within a single large set of conditions.
There is largely little difference between the time it takes to find a condition using if,if statements or if-elseif statements. Also the size of the resulting scripts were only negligibly different compared to the difference in execution time.
At first I thought that since the switch statement breaks execution after it matches its value especially since I was using random numbers, that this could account for the time difference, but that also had no bearing. Setting $var=999999 in the below statements had little effect on the faster execution time of the switch statement.
If-Elseif
<?
$var=rand(0,1000000);
if ($var==0)
{
echo "found 0";
}
elseif ($var==1)
{
echo "found 1";
}
elseif ($var==2)
{
echo "found 2";
}
....
?>
If,If
<?
$var=rand(0,1000000);
if ($var==1)
{
echo "found 1";
}
if ($var==2)
{
echo "found 2";
}
if ($var==3)
{
echo "found 3";
}
....
?>
Switch
<?
$var=rand(0,1000000);
switch ($var)
{
case 1:
echo "found 1";
break;
case 2:
echo "found 2";
break;
case 3:
echo "found 3";
break;
....
?>
Of course, the if else construct is a bit more powerful for more complex condition testing, but if you only have a simple variable to match up against a known set of values, I guess the winner is the switch condition!
Comments (7) 01/27/2008 10:06am
