网上看了有些代码有些错误，主要是下面实例中的0查找不到，这里重新更正了下

思想：循环数组有一边是有序的，首先先判断哪一边有序（通过将当前mid点与最左边节点比较），然后查看是否在有序边上

代码如下

#include<iostream>
#include<assert.h>
using namespace std;
int Binary_Search(int *a,int low,int high,int value)
{
	int mid=(low+high)/2;
	if(a[mid] == value)
	return mid;
    if(a[mid]>=a[low])       //左有序
    {
        if(a[low]<=value && value<a[mid])        //说明value在左边，直接二分查找
        {
            return Binary_Search(a,low,mid,value);
        }
        else                                       //value在右边
        {
            return Binary_Search(a,mid+1,high,value);
        }
    }
    else                    //右有序
    {
        if(a[mid]<=value && value<=a[high])
        {
            return Binary_Search(a,mid,high,value);
        }
        else
        {
            return Binary_Search(a,low,mid-1,value);
        }
	}
}
int main()
{
	int A[10] = {7,8,9,0,1,2,3,4,5,6};
	int p = Binary_Search(A,0,9,0);
	cout<<p<<endl;
	return 0;
}

非递归写法如下：

#include<iostream>
#include<stdio.h>
#include<assert.h>
using namespace std;
int Binary_Search(int *A,int size,int value)
{
	assert(A != NULL);
	int low = 0;
	int high = size - 1;
	while(low <= high)
	{
		int mid = (low + high) / 2;
		if(A[mid] == value)
			return mid;
		if(A[low] <= A[mid])//左有序,注意‘=’的使用
		{
			if(A[low] <= value && value <= A[mid])
				high = mid - 1;
			else 
				low = mid + 1;
		}
		else//右有序
		{
			if(A[mid] <= value && A[high] >= value)
				low = mid + 1;
			else
				high = mid - 1;
		}
	}
}
int main()
{
	int A[10] = {7,8,9,0,1,2,3,4,5,6};
	cout<<Binary_Search(A,10,5);
	return 0;
}