function binarySearch(&$arr,$findVal,$start,$end) //1 { if($end<$start) { echo "找不到该数"; } $mid = round(($end+$start)/2); if($findVal>$arr[$mid]) { binarySearch($arr,$findVal,$mid+1,$end); } else if($findVal<$arr[$mid]) { binarySearch($arr,$findVal,$start,$mid-1); } else { echo "找到这个数,下标是$mid"; } } $arr = array(2,3,5,8,9); echo binarySearch($arr,3,0,count($arr)-1);
&起到什么作用?
$mid为什么要加1减1?
习惯受伤