无效*指向清单中的无效*

Question

I have a list like so:

void * head = [void * a] --> [void * b] --> [void * b] --> NULL

Given void * head , how can I iterate through the list?

Each void * points to another void * , with the final item in the list pointing to NULL .

I think I need to use void ** , but I'm not completely sure. Each item in the list is not in contiguous memory.

Answer 1

I have a list like this [...]

This is not exactly a list - it is a multi-level pointer with the level unknown at compile time.

I think I need to use void ** , but I'm not completely sure

Yes, you are right! You can dereference the pointer one level at a time.

Here is what you can do:

• Set up a while loop that ends when head is NULL
• Inside the loop, make a void **next , and assign head to it
• Now dereference next, and assign the result to head , like this: head = *next
• Continue with the loop until head is NULL .

Each iteration of the loop removes another level of indirection, until the final pointer is reached.

Answer 2

void *node = head;
while(node) {
    // do stuff with the node
    node = *((void**)node);
}