递归实现二分法查找

用递归的方法实现二分法查找（二分法查找的前提是数据有序）

#include <stdio.h>
#include <stdlib.h>
// 二分查找-数据有序
int _binary_find(int arr[],int left,int right,int key)
{
	if(left >= right) return -1;
	int p = (left+right)/2;
	if(arr[p] == key) return p;
	if(arr[p] > key)
		return _binary_find(arr,left,p,key);
	else
		return _binary_find(arr,p+1,right,key);
}

int binary_find(int arr[],size_t len,int key)
{
	return _binary_find(arr,0,len,key);
}
int main()
{
	int arr[10] = {};
	for(int i=0; i<10; i++)
	{
		arr[i] = i+10;
		printf("%d ",arr[i]);
	}
	printf("\n");
	printf("%d\n",binary_find(arr,10,18));
}