<?php
set_time_limit(0);
define('NUMBER_OF_TESTS', 5000);
define('ARRAY_SIZE', 200);

function quicksort( $array )
{
 $cur = 1;
 $stack[1]['l'] = 0;
 $stack[1]['r'] = count($array)-1;

 do
 {
  $l = $stack[$cur]['l'];
  $r = $stack[$cur]['r'];
  $cur--;

  do
  {
   $i = $l;
   $j = $r;
   $tmp = $array[(int)( ($l+$r)/2 )][1];

   do
   {
    while ( $array[$i][1] < $tmp )
     $i++;

    while ( $tmp < $array[$j][1] )
     $j--;

    if ( $i <= $j )
    {
     $w = $array[$i];
     $array[$i] = $array[$j];
     $array[$j] = $w;

     $i++;
     $j--;
    }

   } while ( $i <= $j );


   if ( $i < $r )
   {
    $cur++;
    $stack[$cur]['l'] = $i;
    $stack[$cur]['r'] = $r;
   }
   $r = $j;

  } while( $l < $r );

 } while( $cur != 0 );

 return $array;
}

function microtime_float()
{
 return microtime(true);
}

function set(&$array)
{
 for ($i = 0; $i<ARRAY_SIZE; $i++)
 {
  $array[$i][0] = "user ".$i;
  $array[$i][1] = rand(10, 100);
 }
}

echo "<pre>";

// ----------

$time = microtime_float();
set($array);
$time = microtime_float()-$time;
$settime = ($time*NUMBER_OF_TESTS)/2;

// ----------

function usort_function($a, $b)
{
 return ($a[1] == $b[1]) ? 0 : ($a[1] < $b[1]) ? -1 : 1;
}

$time = microtime_float();
for ($i = 1; $i<NUMBER_OF_TESTS; $i++)
{
 if ($i&1)
  set($array);
 usort($array, 'usort_function');
}
$time = microtime_float()-$time;
echo "usort: ".$time."-".$settime."=<br>".($time-$settime)."<br>";

echo "<br>";

// ----------

$time = microtime_float();
for ($i = 1; $i<NUMBER_OF_TESTS; $i++)
{
 if ($i&1)
  set($array);
 $array = quicksort($array);
}
$time = microtime_float()-$time;
echo "quicksort: ".$time."-".$settime."=<br>".($time-$settime)."<br>";

echo "</pre>";
?>