Question

I happens to read this http://code.google.com/speed/articles/optimizing-php.html

It claims that this code

$description = strip_tags($_POST['description']);
echo $description;

should be optimized as below

echo strip_tags($_POST['description']);

However, in my understanding, assignment operation in PHP is not necessarily create a copy in memory.

This only have one copy of “abc” in memory.

$a = $b = "abc";

It consumes more memory only when one variable is changed.

$a = $b = "abc";
$a = "xyz";

Is that correct?

Answer 1

should be optimized as below

It’s only a good idea if you don’t need to store it, thereby avoiding unnecessary memory consumption. However, if you need to output the same thing again later, it’s better to store it in a variable to avoid a another function call.

Is that correct?

Yes. It’s called copy-on-write.