#include<stdio.h>
int binary_search(int arr[],int i,int sz)//arr是一个指针
{
int left = 0;
int right = sz - 1;
while (left<=right)
{
int mid = (left + right)/2;//中间元素下标
if (arr[mid] < i)
left = mid+1 ;
else if (arr[mid] > i)
right = mid-1;
else
return mid;
}
return -1;
}
int main()
{
//二分查找
//在一个有序数组中找到具体的某个数
//找到了返回下标,找不到返回-1
int arr[] = {1,2,3,4,5,6,7,8,9,10};
int k = 10;
int sz = sizeof(arr)/sizeof(arr[0]);
int m=binary_search(arr,k,sz );
if (m == -1)
printf("找不到指定数字");
else
printf("找到了,下标是%d", m);
return 0;
}