NYCPHP Meetup

[Rolan Yang]

David Mintz wrote:
>
>
> I heard somewhere that it does cost to reference/de-reference for no 
> good reason, and that if youi're not going to write to it, pass it by 
> value not reference. But I don't remember when or where, so don't ask 
> me support that with things like facts or sources.
>
> -- 
> David Mintz
> http://davidmintz.org/
>

Wow, what a shocker.
I just ran a quick test and passing by reference is SLOWER by a factor 
of 1000.
I'm running the script below on a  AMD Athlon XP 2200+ with 1GB RAM   
Redhat Fedora Core 5.
(if the email is mangled, you can grab the source from 
http://omnistep.com/phpstuff/ )
You need to supply a reasonably large file and repoint the $filename 
variable to it before running.

<?php

// Tests speed of passing by reference vs passing by value
// Rolan Yang rolan at omnistep.com Aug 19, 2008


$filename='os-php-cake2-ltr.pdf';  // point this to any fairly large 
file (1+ Megabyte?)

$blobofdata=file($filename); // load blob of data into a variable

if (isset($_SERVER['HTTP_USER_AGENT'])) {$newline="<br>\n";} else 
{$newline="\n";}
$start=microtime(TRUE);

print "Pass by Reference{$newline}";
print "Start: $start{$newline}";

for ($x=0;$x<500;$x++) {
        $a=passByRef($blobofdata); // passes it by reference 500 times
}

$end=microtime(TRUE);

print "End: $end{$newline}Total=".($end-$start).$newline.$newline;

$start=$end;
print "Pass by Value{$newline}";
print "Start: $start{$newline}";

for ($x=0;$x<500;$x++) {
        $a=passByValue($blobofdata); // passes it by value 500 times
}

$end=microtime(TRUE);
print "End: $end{$newline}Total=".($end-$start).$newline;


function passByRef(&$bla) {
        return $bla;
}

function passByValue($bla) {
        return $bla;
}

?>