The functions work but they are not passing edge cases. The remove after function needs to throw an exception when the they try to remove the trailer node. The remove before function needs to throw an exception when they try to remove the header node. This is a double linked list class using a struct for the node, A snipped of the header can be seen below. My move constructor needs to handle trying to move an empty list.

struct DLListNode {

int obj;

DLListNode *prev, *next;

// constructor

DLListNode(int e=0, DLListNode *p=nullptr, DLListNode *n=nullptr): obj(e), prev(p), next(n){}

};

// doubly linked list class

class DLList {

private:

DLListNode header, trailer;

public:

DLList::DLList() : header(0), trailer(0)

{

//set next and prev to values of trailer and header

header.next = &trailer;

trailer.prev = &header;

}

DLList(const DLList& dll); // copy constructor

DLList(DLList&& dll); // move constructor

~DLList(); // destructor

....

---------------------------------------

DLList::DLList(DLList &&dll)// move constructor

{

// moving values without copying

if (!this->is_empty())

{

header.next = dll.header.next;

trailer.prev = dll.trailer.prev;

dll.header.next->prev = &header;

trailer.prev->next = &trailer;

dll.header.next = &dll.trailer;

dll.trailer.prev = &dll.header;

}

else

{

header.next = &trailer;

trailer.prev = &header;

}

}

int DLList::remove_after(DLListNode &p)

{

if (this->is_empty())

throw("Empty List");

if (&p == &trailer)

{

throw("Error: reached the end of list");

}

DLListNode *temp = p.next;

temp->next->prev = &p;

p.next = temp->next;

int nodes_obj = temp->obj;

delete temp;

return nodes_obj;

}

int DLList::remove_before(DLListNode &p)

{

if (this->is_empty())

{

throw("Empty List");

}

else

{

DLListNode *temp = p.prev;

temp->prev->next = &p;

p.prev = temp->prev;

int nodes_obj = temp->obj;

delete temp;

return nodes_obj;

}

}