#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
int binary_search(int a[],int k,int s)
{
int left = 0;
int right = s-1;
while(left <= right)
{
int mid = (left + right)/2;
if(a[mid]>k)
{
right = mid -1;
}
else if(a[mid]<k)
{
left = mid+1;
}
else
return mid;
}
return -1;
}
int main()
{
int arr[] = {1,2,3,4,5,6,7,8,9,10};
int key = 17;
int sz = sizeof(arr) /sizeof(arr[0]);
//找到了就返回找到的位置的下标，找不到返回-1
int ret = binary_search(arr,key,sz);
if(-1 == ret)
{
printf("找不到\n");
}
else
{
printf("找到了，下标是：%d\n",ret);
}
return 0;
}