php array reference passing to function

Question

I have a question that I cannot find an answer.

I'm constructing a very big array that contain hex values of a file (like $array[0]=B5 $array[1]=82 and so on until $array[1230009])

When I create a function to manipulate some offsets in that array and pass the $array as reference ( function parse(&$array) { ... }) it takes WAY longer than if I pass the array normaly ( function parse($array) { ... }) ..

How is that possible ?

PS: Is there any faster way not to use array at all ? Just to use a $string = "B5 82 00 1E ..etc", but I need to track the Offset as i advance in reading hex values as some of this values contains lengths"

It takes longer to pass the array, or it takes longer to perform your function on the array that you pass? Also, this is not a RAM efficient means of referencing each byte of a file. You should use strings instead methinks. — crush, Feb 14 '12 at 21:16
possible duplicate of [In PHP (>= 5.0), is passing by reference faster?](http://stackoverflow.com/questions/178328/in-php-5-0-is-passing-by-reference-faster) — PeeHaa, Feb 14 '12 at 21:17
it takes like 30 seconds to perform the function on the array (by reference) and 2 second to perform the function on the array by normal passing — pufos, Feb 14 '12 at 21:18

score 3 · Accepted Answer · answered Feb 14 '12 at 21:19

There are some informations that might help in the following article : Do not use PHP references

Close to the end of that post, Johannes posts the following portion of code (quoting) :

function foo(&$data) {
    for ($i = 0; $i < strlen($data); $i++) {
        do_something($data{$i});
    }
}

$string = "... looooong string with lots of data .....";
foo(string);

And a part of the comment that goes with it is (still quoting) :

But now in this case the developer tried to be smart and save time by passing a reference.
But well, strlen() expects a copy.
copy-on-write can't be done on references so $data will be copied for calling strlen(), strlen() will do an absolutely simple operation - in fact strlen() is one of the most trivial functions in PHP - and the copy will be destroyed immediately.

You might well be in a situation like this one, considering the question you are asking...

EDITED: Ok I understand that now but : How to use strings like $string = "B5 82 00 1E .... etc" ? But I need to perform a login on every hex value and need to keep the offset as I advance in reading it — pufos, Feb 14 '12 at 21:22

php array reference passing to function

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