Void print_back();

};

//-----------------------------------

template <class Data>

List <Data>::~List(){

if (pbeg!=0){

Node *pv = pbeg;

while (pv){

pv = pv->next; delete pbeg;

pbeg = pv;}

//--------------------------------------

template <class Data>

void List <Data>::print(){

Node *pv = pbeg;

cout << endl<< "list: ";

while (pv){

cout << pv->d << ' ';

pv = pv->next;}

cout << endl;

}

//--------------------------------------------

template <class Data>

void List <Data>::print_back(){

Node *pv = pend;

cout << endl << " list back: ";

while (pv){

cout << pv->d << ' ';

pv = pv->prev;}

cout << endl;

}

//-----------------------------------

template <class Data>

void List <Data>::add(Data d){

Node *pv = new Node(d);

if (pbeg == 0)pbeg = pend = pv;

else{

pv->prev = pend;

pend->next = pv;

pend = pv;}

}

//----------------------------------------------------

template <class Data>

Node * List <Data>::find(Data d){

Node *pv = pbeg;

while (pv){

if(pv->d == d)break;

pv = pv->next;

}

Return pv;

}

//------------------------------------------------------------

template <class Data>

Node * List <Data>::insert(Data key, Data d){

if(Node *pkey = find(key)){

Node *pv = new Node(d);

pv->next = pkey->next;

pv->prev = ркеу;

pkey->next =pv;

i f (ркеу!= pend)(pv->next)->prev = pv;

else pend = pv;

return pv;}

return 0:

}

// -------------------------------------------

template <class Data>

bool List <Data>::remove(Data key){

if(Node *pkey = find(key)){

i f (pkey == pbeg){

pbeg = pbeg->next; pbeg->prev = 0:}

else if (pkey == pend){

pend = pend->prev; pend->next = 0:}

else {

(pkey->prev)->next = pkey->next;

(pkey->next)->prev = pkey->prev;}

Delete pkey;