一个函数实现一个整形有序数组的二分查找

一个函数实现一个整形有序数组的二分查找

int binary_search(int arr[], int k, int left, int right)
{
	
	while(left <= right)
	{
		int mid = left + (right-left)/2;  //mid是数组下标
			if(arr[mid] < k)  //arr[mid]为数组元素
		{
			left = mid + 1;
		}
		else if(arr[mid] > k)
		{
			right = mid + 1;
		}
		else 
		{
			return mid;
		}
	}
	return -1;
}
int main()
{
	int arr[10] = {1,2,3,4,5,6,7,8,9,10};
	int k = 5;
	int sz = sizeof(arr)/sizeof(arr[0]);
	int res = binary_search(arr,k,0,sz-1);  //这里0为left;   sz-1为right
	if(res == -1)
	{
		printf("找不到.....\n");
	}
	else
	{
		printf("找到了，下标为%d\n",res);
	}
	return 0;
}

运行结果