php: IF versus SWITCH
Often times, a PHP developer will need to display different information depending on the circumstances. In the case of our SE Content Management System, there are dozens of these scenarios: from where to display the image gallery on a particular page to whether or not to show breadcrumbs. In every instance, we have to determine how to evaluate the situation. Is it a simple show or don’t show item, or are there several possible outcomes?
In this example, we will be using the months of the year as our ‘variable’.
First we must define the current month:
php:<?php $currentmonth = date("m"); ?>Now, if we wanted to introduce special code in only one month, such as saying ‘Happy New Year’ in January, then an IF statement would work just fine:
php:<?php if ($currentmonth == '01') { ?>You see that the if statement is always enclosed in parenthesis and the result is always enclosed in squiggly brackets. In this example, we chose to output in HTML, so we had to close and re-open our php tags. We could have also chosen to do this:
<strong>Happy New Year!</strong>
<?php } ?>
php:<?php if ($currentmonth == '01') {Lets say that you needed a ‘Happy New Year’ for January, ‘Happy Valentines Day’ for February, ‘Happy Thanksgiving’ for November and ‘Merry Christmas’ for December. An If statement is not practical for this situation, so we need to use the php SWITCH statement instead. With a switch statement, we first present the variable:
echo "Happy New Year!";
} ?>
php:<?php switch ($currentmonth) {Next, we present each ‘case’, followed by the intended output and a break. Lets start with January, which is ‘01′:
php:case 01:
echo "Happy New Year";
break;
Now, lets put it all together:
php:<?php switch ($currentmonth) {
case 01:
echo "Happy New Year";
break;
case 02:
echo "Happy Valentines";
break;
case 11:
echo "Happy Thanksgiving";
break;
case 12:
echo "Merry Christmas";
break;
default:
echo "Just another month...";
}
?>
You see that we also added a ‘default’ condition for all other months. This is, of course not required, but it is often useful.
Compatibility:
As this is a php tutorial, a php-capable server is required for this code to function properly.
That’s all folks!
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Tags: php
January 29th, 2008 at 1:12 pm
Pretty good comparison/tutorial on using switch over if/else. What I would really like to know is if there is any sort of speed increase/decrease.
February 1st, 2008 at 5:09 am
Dave, Switch should be slightly faster than if, when there are several cases, but if should be quicker for the first example. This is debatable though. Hard to test!
Great little tutorial though.Probably the simplest explanation of the switch function I’ve seen on the net.
February 2nd, 2008 at 10:08 am
Well said explanation Deanzod, and thank you for your kind words!
September 22nd, 2009 at 4:19 pm
I recently experimented the performance, and switch is certainly faster.
What I did was auto-generated code for switch case vs. if-else for 500+ numbers and corresponding values. Switch case was approx. 20% faster at all times.
January 8th, 2010 at 6:40 pm
To take this one step further, it's worth pointing out that both Switch & If should be avoided if a conditional statement isn't actually necessary at all.
In this example, let's say there was a custom message for *all twelve* months. The fastest and cleanest method would be to build an array of messages:
$messages = array("message 1", "message 2", "message 3" … etc. … );
And then to simply access the appropriate message using the month:
echo $messages[$currentmonth];