Linked List C++ Code Implementation

#include<iostream.h>
#ifndef class_H
#define class_H
typedef int ListElementType;

class List
{
public:
	

	List();
	List(ListElementType [],const int);
	void insert(const ListElementType &elem);//Only insertion
	void append(List &L);//append Function
 
    List * copy();//Copy function
	bool first(ListElementType &elem);
	bool next(ListElementType &elem);
 	bool traverse(); //Traverse the list
	bool before(const ListElementType );//Insert Berfore agiven element
    void saveTofile();
	List LoadFromfile();
 
private:
	 
	 struct NODE;
	 typedef NODE* Link;
	 struct NODE
	 {
        ListElementType elem;
		Link next;
	 };
	 Link head;
	 Link current;
	 Link tail;
      int counter;  
	
	 
	  
};
#endif

#include<fstream.h>
#include"Class.h"
List::List()
{
   head=0;
   current=0;
   tail=0;
   counter=0;
}
void List::insert(const  ListElementType &elem)
{ 
    counter++;
	Link addedNode=new NODE;
	addedNode->elem=elem;
	if(head==0)
	{
		head=addedNode;
		 
	}
	else 
	   tail->next=addedNode;
//
       tail=addedNode;
       tail->next=0;
	  

}
bool List::first(ListElementType &elem)
{
	 if(head==0)
	 return false;
     
	 elem=head->elem;
	 current=head;
	  
	 return true;
}
bool List::next(ListElementType &elem)
{
	if(current->next==0) {return false;}
  
	else 
	{
	current=current->next;
	elem=current->elem;
	return true;
	}

    
	  
}
////////// ///Added Functions  ////////////
bool List::traverse()
{

  if(head==0)return false;
 
  Link prev=head;
  while(prev!=0)
  {
	  cout<<prev->elem<<",";
	  prev=prev->next;
  }
  cout<<endl;
  return true;
} 

List::List(ListElementType a[],const int size)//Constructor that insert ARRAY in the list
{
   head=0;
   current=0;
   tail=0;
   counter=0;

    for(int i=0;i<size;i++)
		 insert(a[i]);

}
//////// ////////////////////
void List::append(List &L)
{
	tail->next=L.head ;
	tail=L.tail;


}
///////////////////////////////////////////////////	   
List * List::copy()//copy function
{
	List *L=new List;
	Link prev=head;

	for(prev=head;prev!=0;prev=prev->next)
	{
		
		L->insert(prev->elem);
         
	}
 
	return L;
}
List List::LoadFromfile() 
{
	List L;
	ifstream in("file.txt");
    ListElementType elem;
	while(true)
	{
		in>>elem;
		if(in.eof())break;
		L.insert(elem);
		
	}

	return L;
}
void  List::saveTofile()
{
	
	ofstream out("file.txt");
    ListElementType elem;
	first(elem);
	bool notEnd;
	while(true)
	{
	
		out<<elem<<" ";
		 notEnd=next(elem);
		if(!notEnd)break;
	}

	 
}

#include<iostream.h>
#include"Class.h"
void main()
{
	int a[6]={4,6,3,3,10,2};
	List L1 ,L2(a,6);
	List *ptr;
	int i;
	cout<<"Enter items to add to list,add 0 to stop "<<endl;
	cin>>i;
	while(i!=0)
	{
		L1.insert(i);
			cin>>i;
	}
	cout<<"Here are the items in the list.\n";
 	L1.traverse();
	L1.saveTofile();
	L2.traverse();
	List L3=L2.LoadFromfile();
	L2.append(L1); 
	ptr=L2.copy();
	ptr->append(L2);
    L2.traverse();
	ptr->traverse(); 
    L3.traverse();

 

}