写一个二分查找的函数.txt

#include<stdio.h>
#include<string.h>
int find(int *arr,int k,int y);
int main()
{
	int k;
	int arr[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
	int y = (sizeof(arr) / sizeof(arr[0])) - 1;
	scanf("%d", &k);
	int ret = find(arr,k,y);
	if (ret!=-1)
	printf("找到了，下标是%d\n", ret);
	else printf("没找到！\n");
	return 0;
}

int find(int *arr,int k,int y)
{
	int left = 0;
	int right = y-1;
	int mid = 0;
	while (left<=right)
	{
		mid = (left + right) / 2;
		if (arr[mid] < k)
		{
			left = mid + 1;
		}
		else if (arr[mid]>k)
		{
			right = mid - 1;
		}
		else return mid;
	}
	if (left > right)
		return -1;
}