PHP $_GET performance

Question

Is one option generally faster than the other?

Option A: $var = $_GET['param']; and then referencing $var through the script.
Option B: Referencing $_GET['param'] in each occurrence through the script.

Thanks!

Answer 1

The difference in performance if any will be negligible and not worth the effort - so much so that even if you attempted to microtime it the difference would be consumed by random factors.

However Option A is better in terms of creating more sustainable code. e.g. If you ever wish to change the value of $var you can do it from one position in your code.

Simply put this is never going to be the bottleneck in your program.

Answer 2

Benchmarked with 10000000 loops

$var = "bleh";
for ($i=0; $i<10000000; $i++) {
strlen($var);
}

and

$array = array();
$array['blah'] = "bleh";
for ($i=0; $i<10000000; $i++) {
strlen($array['blah']);
}

Results:

• Var: 8.563s - 856.3 nanoseconds per loop
• Array: 8.699s - 869.9 nanoseconds per loop

1.6% difference in speed.

Answer 3

This kind of micro-optimisation is rarely worth thinking about. It's generally best to think about how best to architect your code, and leave such problems to the people writing the runtime of the language.

There are many factors that would be relevant if we really wanted to work out which was more efficient:

• how array access works to perform the ['param'] once or many times
• how superglobals such as $_GET are implemented
• how assignment is implemented (which in PHP uses "copy on write")
• how you pass $var around your code (e.g. as a function parameter) and how that is implemented
• how often you need to read from the variable
• how often you write to the variable

I'm sure there are many more; and, of course, both your program and the PHP runtime its running in are subject to change on all of these points.

Answer 4

Agreed with those that say you're worrying about the wrong level of optimization. (Though, if you really want to obsess over this sort of thing,check out http://www.phpbench.com/)

Your first level of optimization should be optimizing the readability and maintainability of the code. Human clock cycles are far more valuable and expensive (generally speaking) than computer clock cycles. As an added bonus, you'll be very pleasantly surprised how often optimizing for human clock cycles will also make the code remarkably faster.

I strongly recommend Clean Code by Robert C. Martin for an excellent guide to coding style.

Answer 5

A:

$var = $_GET['param']; // and then referencing $var through the script.

Requires a constant time, which is equal to zero in computer science.

B: Referencing

$_GET['param']; // in each occurrence through the script.

Is an ugly approach and is only done by "sloppy" programmers.

Let's say that you have to use $_GET['param'] 10 times on a single page, or in multiple pages, and then you decide that you want to change 'param' to 'p' or 'parameter', then you're out of luck.

You want to initialize 'magic numbers' and 'magic values' to a variable (or a constant), which you can edit later on, and the programmer (whether It's your or someone else) doesn't have to know exactly what it is.

Imagine if programmers would use

if($number == 3.1415)

instead of

if($number == $pi)

it comes down to a similar basis.

So, NO, neither option is generally theoretically faster but option B is going to give you hell later on, and is ugly.

Answer 6

Use $_GET['param'] whenever you can. PHP has to remember $_GET['param']. By making a variable that is equal to $_GET['param'], PHP now has to remember two variables that are exactly the same.

Unless you're going to change the value of the new variable, it's faster to just use $_GET['param']. (Keep in mind, some people like to make new variables simply for readability)