函数的二分查找

#include
int binary_search(int arr[], int x, int sz)
{
	int left = 0;
	int right = sz - 1;
	while (left <= right)
	{
		int mid = (left + right) / 2;
		if (arr[mid] < x)
			left = mid + 1;
		else if (arr[mid] > x)
			right = mid - 1;
		else
			return mid;
	}
	return -1;
}
int main()
{
	int arr[10] = { 1,2,3,4,5,6,7,8,9 };
	int x;
	scanf("%d", &x);
	int sz = sizeof(arr) / sizeof(arr[0]);
	int ret = binary_search(arr, x, sz);//括号里放的是arr,不是arr[10]!!!
	if (ret == -1)
	{
		printf("找不到了");
	}
	else
	{
		printf("找到了,下标是%d", ret);
	}
	return 0;
}