What is quicker, for camelCase to underscores; using preg_replace() or using ord() ?

My guess is the method using ord will be quicker, since preg_replace can do much more then needed.

<?php
function __autoload($class_name){
    $name = strtolower(preg_replace('/([a-z])([A-Z])/', '$1_$2', $class_name));
    require_once("some_dir/".$name.".php");
}
?>

VEYA

<?php
function __autoload($class_name){
// lowercase first letter
$class_name[0] = strtolower($class_name[0]);

$len = strlen($class_name);
for ($i = 0; $i < $len; ++$i) {
    // see if we have an uppercase character and replace
    if (ord($class_name[$i]) > ord('A') && ord($class_name[$i]) < ord('Z')) {
        $class_name[$i] = '_' . strtolower($class_name[$i]);
        // increase length of class and position
        ++$len;
        ++$i;
    }
}

return $class_name;
}
?>

reddi - alınan kod örnekleri StackOverflowQuestion 1589468.

düzenleme, jensgram 'ın dizi-öneri ve bulma sonra array_splice i aşağıdaki ile geldi:

<?php
function __autoload ($string)// actually, function camel2underscore
{
$string  =  str_split($string);
$pos     =  count( $string );
while ( --$pos > 0 )
{
    $lower  =  strtolower( $string[ $pos ] );
    if ( $string[ $pos ] === $lower )
    {
        // assuming most letters will be underscore this should be improvement
        continue;
    }
    unset( $string[ $pos ] );
    array_splice( $string , $pos , 0 , array( '_' , $lower ) );
}
$string  =  implode( '' , $string );
return $string;
}
// $pos could be avoided by using the array key, something i might look into later on.
?>

When i will be testing these methods i will add this one but feel free to tell me your results at anytime ;p