TemplateDoubly, C++ (gcc)

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//g++  7.4.0
//Template Double Linked List
//class code credit internet 
#include <iostream>
using namespace std;
template <class V>
 class node {
public:
V data;
node<V>* next;
node<V>* prev;
};

template <class T>
 class Double_List
 {

node<T>* head, * tail;
 	public:
Double_List(){head=NULL;
	 	tail=NULL;
	 }
 
 		void create_list(T n);
 		void add_begin(T n); 
 		void display();
 		void reverse();
node<T>* gethead() { return head;}
node<T>* gettail(){return tail;}
void after(node<T> *q, T v)
    {
node<T>* p = new node<T>;
       p->data=v;
        p->next=q->next;
        q->next = p;
        p->prev= q;
    }

void before (node<T>* q , T v)
{
node<T> * p= new node<T>;

p->data= v;
p->prev= q->prev;
q->prev = p;
p->next = q;
}

node<T>* delnode(node<T>* begin, T item)
{
node<T>* temp;
if (begin == NULL)
{
cout <<" Empty list \n";
return begin;
}
if (begin->next == NULL){
 if(begin->data == item)
{
  temp = begin;
  begin = NULL;
  delete temp;
  return begin;
}
  else
      {
         cout<<"Item  "<<item<<" isn't found\n";
     return begin;
}

}
   if (begin->data == item)
  {
      temp = begin;  
     begin = begin->next;
     begin->prev= NULL;
    delete temp;
      return begin;
  }
  temp = begin->next;

while (temp->next != NULL)
    {
       if(temp->data == item)
    { 
      temp->prev->next = temp->next;
     temp->next->prev = temp->prev;
    delete temp;
    return begin;
  }

temp = temp ->next;
}
if (temp->data == item)
{
  temp->prev->next= NULL;
 delete temp;
return begin;
}
cout<<"Item  "<<item<<" isn't found\n";
     return begin;
}

void remove();
bool
isempty()
    {
    if (head == NULL)
    return true;
    return false;
    }

};

template <class T>
void Double_List<T>::create_list(T n)
  { 
       node<T> *newnode;
	newnode=new node<T>;
	newnode->data=n;
	 if(head==NULL)
	 {
	 	head=newnode;
	 	newnode->prev=NULL;
	 	newnode->next=NULL;
	 	tail=newnode;
	   }  
	else
	{
		newnode->prev=tail;
		tail->next=newnode;
		newnode->next=NULL;
		tail=newnode;
	}
  }
  template <class T>
  void Double_List<T>::add_begin(T n)
  {
  	if(head==NULL)
  	{
  		cout<<" NO element, ist create : \n";
  		return;
	  }
  	 node<T> *temp=new node<T>;
  	 temp->data=n;
  	 temp->prev=NULL;
  	 temp->next=head;
  	 head->prev=temp;
  	 head=temp;
  	 cout<<" Insert Sucessfull.... \n";
  }
  
  
  
  template <class T>
  void Double_List<T>::display()
  {
  	node<T> *q;
  	 if(head==NULL)
  	 {
  	 	cout<<" list empty.. \n";
  	 	return;
	   }
	   q=head;
	   cout<<" The Double Linked list is \n";
	   while(q!=NULL)
	    {
	    	cout<<q->data<<"<-->";
	    	q=q->next;
		}
  }
  template <class T>
  void Double_List<T>::reverse()
  {
  	node<T> *r;
  	 if(tail==NULL)
  	 {
  	 	cout<<"EMPTY list: \n";
  	 	return;
	   }
	else
	{
		r=tail;
	 while(r!=NULL)
	 {
	 	cout<<r->data<<" <--> ";
	    
	 	r=r->prev;
	 	
	 }cout<<"reverse sucessful: \n";
	}
  }

template <class T>
void Double_List<T>:: remove()
    {
    
    if(isempty())
    {
    cout<<"is empty";
        
    }
else if (head == tail){
     
            delete head;
        head= tail =NULL;
        }
        else
        {
        node<T>* temp, *temp2;
            temp2= tail;
            temp= head;

while (temp->next!= NULL)
{
temp2= temp;
temp=temp->next;
}
tail = temp2;
tail->next=NULL;
            delete temp;
while(temp->prev != NULL)
{ temp= temp2; temp2= temp2->prev;}
head = temp; tail->prev= NULL;
delete temp2;
        }
    }

int main()
{

Double_List<int> dl;
Double_List<char> cl;
dl.create_list(10);
dl.create_list(11);

dl.create_list(12);

dl.add_begin(9);
dl.after(dl.gethead()->next->next,7);
dl.before(dl.gettail()->prev,8);

dl.display();
cout<<endl;
dl.reverse();
cl.create_list('H');
cl.create_list('!');
cl.after(cl.gettail(),'!');

cl.display();
cout<<endl;
cl.reverse();
return 0;
}

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Compilation time: 0.53 sec, absolute running time: 0.16 sec, cpu time: 0.01 sec, memory peak: 5 Mb, absolute service time: 0,77 sec