//有一个数组  {1,2,3,4,5,6,7,8,9,12,13,45,67,89,99,101,111,123,134,565,677} 查找数组中是否有指定的某一个数.

1 /** 2   *---------------------------------------- 3   * Time:2016-06-21 | 二分查找 4   *--------------------------------------- 5   */  6 function binarySearch(&$arr,$findVal,$leftIndex,$rightIndex){ 7   if($rightIndex < $leftIndex){ 8     echo "哇哇哇,找不到o(︶︿︶)o 唉"; 9     return;10   }11   // @ 取中间的key12   $middleIndex=round(($rightIndex+$leftIndex)/2);13   if($findVal > $arr[$middleIndex]){14     binarySearch($arr,$findVal,$middleIndex+1,$rightIndex);15   }else if($findVal < $arr[$middleIndex]){16     binarySearch($arr,$findVal,$leftIndex,$middleIndex-1);17   }else{18     echo "哇哇哇找到你了o(∩_∩)o 哈哈。下标是$middleIndex";19   }20 }21     $arr=array(1,2,3,4,5,6,7,8,9,12,13,45,67,89,99,101,111,123,134,565,677);22     print_r(binarySearch($arr,89,0,count($arr)-1));