Step by Step solution about How to resolve the algorithm Doubly-linked list/Element insertion step by step in the C programming language

The provided code is a function called insert that inserts a new link (newlink) into a doubly linked list. The function modifies the list so that newlink is inserted between anchor and anchor's next element.

Here is how the code works:

1. The function insert takes two pointers to link structures: anchor and newlink. anchor represents the link before the insertion point, and newlink represents the link to be inserted.

2. The first line of the function sets newlink->next to anchor->next. This means that newlink will point to the link that was originally after anchor.

3. The second line of the function sets newlink->prev to anchor. This means that newlink will point to anchor as the link before it.

4. The third line of the function sets (newlink->next)->prev to newlink. This means that the link that was originally after anchor will now point to newlink as the link before it.

5. The fourth line of the function sets anchor->next to newlink. This means that anchor will now point to newlink as the link after it.

After these four lines of code are executed, newlink has been successfully inserted into the doubly linked list between anchor and anchor's next element.

Here is an example of how the insert function can be used to insert a new link into a doubly linked list:

// Initialize the doubly linked list
link a, b, c;
a.next = &b;
a.prev = NULL;
a.data = 1;
b.next = NULL;
b.prev = &a;
b.data = 3;

// Create a new link to insert
link c;
c.data = 2;

// Insert the new link into the doubly linked list
insert(&a, &c);

After the insert function is called, the doubly linked list will look like this:

a -> c -> b

void insert(link* anchor, link* newlink) {
  newlink->next = anchor->next;
  newlink->prev = anchor;
  (newlink->next)->prev = newlink;
  anchor->next = newlink;
}


link a, b, c;
a.next = &b;
a.prev = null;
a.data = 1;
b.next = null;
b.prev = &a;
b.data = 3;
c.data = 2;


insert(&a, &c);