int binary_search(int arr[], int k,int sz)//形参和实参数字相同,是支持的
{
int left = 0;
int right = sz - 1;
while (left<=right)
{
int mid = (left + right)/2;
if (arr[mid] > k)
{
right = mid - 1;
}
else if(arr[mid] < k)//如果不写else,则是并列问题,输出有问题
{
left = mid + 1;
}
else
{
return mid;//mid就是下标
}
}
return -1;
}
int main()
{
int arr[] = {1,2,3,4,5,6,7,8,9,10};
int k =7;
int sz = sizeof(arr) / sizeof(arr[0]);
int ret = binary_search(arr, k,sz);
if (ret == -1)
{
printf("找不到指定的数字\n");
}
else
{
printf("找到了,下标是:%d\n", ret);//先写函数怎么用,再去实现
}
return 0;
}