二分查找法

$arr = array(4,58,11,34,88,45,32,54,63,78);

function binary($arr,$bnum)
{
 if(is_array($arr) && count($arr) > 0)
 {
  sort($arr);
  $start = 0;
  $end = count($arr)-1;
  $mid = -1;
  while($start <= $end)
  {
   $mid = floor( ($start+$end)/2 );
   if($arr[$mid] == $bnum)
   {
    return $arr[$mid];
   }else if($arr[$mid] < $bnum)
   {
    $start = $mid +1;
   }else if($arr[$mid] > $bnum)
   {
    $end = $mid - 1;
   }
  }
  return -1;
 }
}
$mm = binary($arr,32);
print_r($mm);