Binary Search(Java)(非递归)

 public static int rank(int[] array, int k)
 {
     int front = 0, rear = array.length - 1;

     while(front <= rear)   //front = rear时, mid必与front和rear指向同一个元素
     {
         int mid = front + (rear - front) / 2;
         if(k > array[mid]) front = mid + 1;
         else if(k < array[mid]) rear = mid -1;
         else return mid;
     }
     return -1;
 }