PHP查找算法

 1 <?php
 2 function half_search($arr,$search_val) 
 3 {
 4     $low = 0;
 5     $high = count($arr) - 1;
 6     while($low <= $high) 
 7     {
 8         $mid = ceil(($low + $high) / 2);
 9         $mid_val = $arr[$mid];
10         if($mid_val < $search_val) 
11         {
12             $low = $mid + 1;
13         }
14         else if($mid_val > $search_val) 
15         {
16             $high = $mid - 1;
17         }
18         else 
19         {
20             return $mid_val;
21         }
22     }
23 }
24 $arr = array(0,1,2,3,4,5,6,7,8,9);
25 var_dump(half_search($arr,8));