How to programmatically dereference pointer?

Question

A weird interview question I had yesterday

Given a void *p pointer, and a int a = 1; how to dereference to any level pointers?

For example,

if input is 1, then you can get the data by *(int *)p

if input is 2, then you can get the data by **(int **)p

if input is 3, then you can get the data by ***(int ***)p

but what if the input is n ? how can you get the data by *xN(int *xN)p ?

I completely had no idea.

Answer 1

Not at all tested, but I think this recursive solution is approximately right:

int get_pointer(void* p, int n)
{
    if (n==1) return *p;
    return get_pointer((void*)(*(int*)p), n-1);
}

Answer 2

Something like this:

int dereference(void *p, int n) {
    for (int i = 0; i < n; i++) {
        p = *((void **) p);
    }

    return (int)p;
}

Answer 3

烦恼：您可以使用for循环或运行input时间的递归函数，并在每次循环中取消对指针的引用一次，将结果传递给下一次迭代。