二分查找

#include<iostream>

using namespace std;

int BinarySearch(int array[] ,int n ,int value)
{
    int left = 0;
    int right = n - 1;
    while(left <= right)
    {
       int middle = left + ((right - left) >> 1);//移位防止溢出
       if(array[middle] > value)
           right = middle - 1;
       else if(array[middle] < value)
           left  = middle + 1;
       else 
           return middle;
    }
    return -1;
}

int main()
{
  int array[] = {1,2,3,9,5,6,7,8};
  int i = BinarySearch(array,8,9);
  cout<<"i = "<<i<<endl;
  cout<<"array["<<i<<"] = "<<array[i]<<endl;
  while(true)
     ;
  return 0;
}