1 <?php
2 function search($arr, $num) {
3 $len = count($arr);
4
5 $start = 0;
6 $end = $len - 1;
7 $mid = floor(($start + $end) / 2);
8
9 while($start <= $end) {
10 echo $start, ':', $mid, ':', $end, '<br />'; //输出查找流程
11
12 if ($num == $arr[$mid]) {
13 return $mid;
14 }elseif ($num > $arr[$mid]) {
15 $start = $mid + 1;
16 } elseif ($num < $arr[$mid]) {
17 $end = $mid - 1;
18 }
19 $mid = floor(($start + $end) / 2);
20 }
21 return -1;
22 }
23
24 $search_arr = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
25 echo '4的索引值为:', search($search_arr, 4);
