Function effeciency

Anon

Firstly, somet weird... I can only see one other post in this entire board (Coding Help)...

Anyways, I'm wondering if anyone knows which is more efficient:

<?php

startTable('table title');
echo 'content here';
endTable()

<?php

drawTable('table title', 'content here');

And if it's the second, up to what length(ish) string would this stop being more efficient?

Thanks,

Danny

Anon

I think it depends entirely on what startTable, drawTable and endTable are...

Anon

They output the start and end of a table, such as

function tableStart() {
?>
<table border=1>
<tr><td>
<?php
}

there's a little more to it, but it's quite simple like that one. I just wondered if passing a huge string into a function was bad, and whether I should make 2 calls (I just thought it'd be a bit neater having the start and end of the table in one function)

Anon

No, the size of the string isn't that worrying. PHP's memory works on reference-counting scheme. If you have

$a="I am a string.";

it means that "I am a string" gets stored away somewhere and a symbol $a is created to point to it.

If you then go

$b=$a;

Then $b is created to point to the same copy of "I am a string" that $a does.

If you then modify $b, a modified version of the string is created and $b is repointed to that. The same goes if $a is modified.

It's the same when passing arguments to functions - copying and its associated hit on memory only occurs if the function modifies the values of any of its arguments.

As for whether this holds or not when it's a matter of dropping in and out of HTML mode instead of passing the HTML as a string to a function, I have to admit I'm not quite so certain. I tend to suspect that the big block of HTML would be stored by PHP somewhere anyway, and storing it in a value would only mean one more symbol in the list, rather than an extra huge string.

There're some articles at http://www.zend.com/zend/art/ that may be more useful.

Anon

if I use 2 functions (one either side), then the contents isn't really a string, it's just passed right thru, whereas passing it in the function surely means php has to allocate memory to that string within the function??

Anon

Well, considering that PHP4 is compiled, memory still needs to be assigned for the HTML block. The question is whether memory assigned to "nonPHP" text is significantly less than the same text stored as a PHP string. Someone familiar with the internals might know something more on this subject.

PHP3 probably didn't need to assign memory, being interpreted, but it was a lot slower, partly for this reason. A typical spacetime tradeoff.

Anon

I didn't even realise php4 was compiled!

I guess there isn't that much difference then... 🙂

Anon

I have to say it makes me feel like something recently dug up in a peat bog: "Oh, let's chuck a compiler in there to speed things up..."