Is it better call a function every time or store that value in a new variable?

I use often the function sizeof($var) on my web application, and I’d like to know if is better (in resources term) store this value in a new variable and use this one, or if it’s better call/use every time that function; or maybe is indifferent 🙂

Answer

TLDR: it’s better to set a variable, calling sizeof() only once. (IMO)

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I ran some tests on the looping aspect of this small array:

$myArray = array("bill", "dave", "alex", "tom", "fred", "smith", "etc", "etc", "etc");

// A)
for($i=0; $i<10000; $i++) {
  echo sizeof($myArray);
}

// B)
$sizeof = sizeof($myArray);
for($i=0; $i<10000; $i++) {
  echo $sizeof;
}

With an array of 9 items:

A) took 0.0085 seconds
B) took 0.0049 seconds

With a array of 180 items:

A) took 0.0078 seconds
B) took 0.0043 seconds

With a array of 3600 items:

A) took 0.5-0.6 seconds
B) took 0.35-0.5 seconds

Although there isn’t much of a difference, you can see that as the array grows, the difference becomes more and more. I think this has made me re-think my opinion, and say that from now on, I’ll be setting the variable pre-loop.

Storing a PHP integer takes 68 bytes of memory. This is a small enough amount, that I think I’d rather worry about processing time than memory space.