CODEWITHSUNDEEP
php
David19801
David19801

Reputation: 11448

php speed testing of conditionals

Assume there is already an if statement on the page.

Now, out of:

a second if statement
else
else if

Which is fastest and which is slowest to run?

Does it matter if $a only takes 2 possible values?

edit: Sample code:

$a=2;
if ($a==1){
...
}

THEN

if ($a==2){
...
}

OR

else {
...
}

OR

else if ($a==2){
...
}

Upvotes: 1

Views: 134

Answers (7)

John Parker
John Parker

Reputation: 54445

This isn't really an answer, but I have to wonder why you think this is important? (If you're worried about optimising things to this level, then I suspect PHP may not be the ideal language.)

In essence, code legibility, consistency and anything that will aid long term maintenance is of way more importance than such micro-optimisation and if you are experiencing performance issues, I'd happily place a large quantity of money (albeit someone else's money) on the fact that it won't be anything to do with if/else/switch, etc. code blocks.

As such, if you're having performance issues, profile the code to find out where the problems lie - don't waste time worrying about the "best" form of conditional statement layout. The "best" form is that which is most easily understood by the programmer(s) working on the project.

Upvotes: 4

tvkanters
tvkanters

Reputation: 3523

The else will simply be the quickest as it has already calculated whether the if statement is true or false. The slowest will be the else if, as it has to called only if the if is false, and has to do an extra check afterwards. The normal if is in the middle, just being an extra check.

You shouldn't base this choice on performance though, but rather on what logic your program should have.

Upvotes: 0

Jesse Bunch
Jesse Bunch

Reputation: 6679

While I admire your craving for speed, I think that measuring the benchmarks of PHP conditionals will be something that will never be conclusive because of the many different variables affecting your output.

With that said, this article shows benchmarks between the if/elseif/else statements as opposed to switch/case statements. It's very interesting to me that switch/case tends to be 15% faster than if/elseif/else.

Hope that helps you feed your uber, enterprise-level cravings!

Upvotes: 0

Alp
Alp

Reputation: 29739

The order of performance from fast to slow:

  • else
  • if
  • elseif

Upvotes: 0

Berry Langerak
Berry Langerak

Reputation: 18859

Which is fastest and which is slowest to run?

I think the difference in speed would be negligible, but the latter would seem to be faster. The former solution will test two distinct conditions, whereas in the latter example, the condition in elseif wouldn't even be evaluated: that won't be necessary. So, I think this should be the fastest:

<?php
$foo = 42;
if( $foo === 42 ) {
}
elseif( $foo === 43 ) { // the condition isn't executed.
}

Upvotes: 0

Pekka
Pekka

Reputation: 449525

Unless you do a million comparisons on the same page (which is unlikely), it will absolutely, fundamentally not matter. Use whatever is best readable.

If you have many if / elseif conditions, also take a look at the switch statement.

Upvotes: 2

knittl
knittl

Reputation: 265341

using a separate if condition will probably be slightly slower than using else, but please, you won't be able to notice the difference even when having a million conditionals. if you really need the speed, then php is not the right choice anyway.

to be definite about the answer you'd have to do profiling of the different flavors of conditionals yourself.

Upvotes: 0

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