Size 10........
Did method1 in 6.19888305664E-5 seconds
Did method2 in 2.88486480713E-5 seconds
Did method3 in 2.21729278564E-5 seconds
Size 100........
Did method1 in 0.0035548210144 seconds
Did method2 in 0.00107884407043 seconds
Did method3 in 0.000940084457397 seconds
Size 1000........
Did method1 in 0.295642137527 seconds
Did method2 in 0.194920063019 seconds
Did method3 in 0.0819511413574 seconds
Size 10000........
Did method1 in 36.8213510513 seconds
Did method2 in 84.960575819 seconds
Did method3 in 14.9312441349 seconds



<?php


foreach(array(10, 100, 1000, 10000) as $size)
{
  // allocate an array....
  $myArray = array();
  for($i = 0; $i < $size; ++$i)
  {
    $myArray[] = $i;
  }

  echo "Size {$size}........<br />";

  // generate an array of indexs to test, we'll have size/2.....
  $randomIndexes = array();
  for ($i = 0; $i < $size/2; ++$i)
  {
    $randomIndexes[] = rand(0, $size-1);
  }

  $time_start = microtime(true);
  foreach($randomIndexes as &$idx)
  {
    getByIndexMethod1($myArray, $idx);
  }
  $time_end = microtime(true);
  $time = $time_end - $time_start;
  echo "Did method1 in {$time} seconds<br />";

  $time_start = microtime(true);
  foreach($randomIndexes as &$idx)
  {
    getByIndexMethod2($myArray, $idx);
  }
  $time_end = microtime(true);
  $time = $time_end - $time_start;
  echo "Did method2 in {$time} seconds<br />";

  $time_start = microtime(true);
  foreach($randomIndexes as &$idx)
  {
    getByIndexMethod3($myArray, $idx);
  }
  $time_end = microtime(true);
  $time = $time_end - $time_start;
  echo "Did method3 in {$time} seconds<br /><hr />";
  flush();

}


function getByIndexMethod1(&$array, $index)
{
  reset($array);
  $idx = 0;
  $ret =& current($array);
  do
  {
    if ($idx == $index)
    {
      return $ret;
    }
    ++$idx;
  }
  while ($ret =& next($array));
  return false;
}

function getByIndexMethod2(&$array, $index)
{
  $tmp = array_values($array);

  if (isset($tmp[$index]))
    return $tmp[$index];
  return false;

}

function getByIndexMethod3(&$array, $index)
{
  $i = 0;
  foreach($array as $key => &$val)
  {
    if ($index == $i)
      return $val;
    $i++;
  }

  return false;
}