C++ Copying elements into new list - c++

Question

I have a problem with copying some elements of list into the new one. It has to be done under one condition: elements that can be copied must be from entered range. The problem is that every single element is copied into newlist. Any suggestions? I want to note that my English is not perfect but I hope you gonna get it. Thank you :)
struct Node
{
Node* next;
int data;
};
struct List
{
Node* head;
Lista();
void push(int);
void addafter(int, int);
void delchosen(int);
void pop();
void print();
int count();
Node* find(int);
void pushback(int);
void popback();
void minmax(int&, int&);
List* range(int, int);
};
List::List()
{
head = NULL;
}
void List::push(int value)
{
Node *p = new Node;
p->data = value;
p->next = head;
head = p;
}
List* List::range(int x, int y)
{
Node* e = head;
List* newlist = new List;
while(e)
{
if(e->data > x && e->data <y)
{
newlist->push(e->data);
}
e = e->next;
}
return newlist;
}
int main()
{
List l;
srand(time(NULL));
const int size = 30;
int* arr = new int [size];
for(int i=0; i<size; i++)
{
arr[i]=rand()%20+1;
l.push(arr[i]);
}
l.range(3, 10);
return 0;
}
Didn't think it will be necessary, but I just have edited the code. Every single function works fine excepting this copying.

Answer 1

You never use the new list. That could probably mislead you. For example you could print or watch in the debugger the old list, which is still contain all the values. It happens sometimes with all the programmers, from freshmen to old long-bearded gurus.
Otherwise code should work:
auto newList = l.range(3, 10);
newList->print();
Bonus: General code review.
It would probably be easier to debug and test the code if you fill the list with deterministic values, rather than random content:
for (int i = 0; i < size; i++) {
l.push(i);
}
Most likely you don't need to allocate newlist on the heap. Use stack allocation:
List List::range(int x, int y) const {
...
List newlist;
...
newlist.push(...);
...
return newlist;
}
While it's nice and funny for self-education and various hacking, you should avoid using homebrew linked lists in the serious code. In C++ we tend to use Standard library facilities instead. Something like:
#include <iostream>
#include <iterator>
#include <list>
int main() {
// Construct original list from brace-initializer list
std::list<int> original{ 1, 2, 3, 4, 5, 6, 7 };
// Get the beginning of the new list by advancing
// beginning of the original list by 2 elements
auto begin = original.cbegin();
std::advance(begin, 2);
// Get the end of the new list by advancing
// beginning of the original list by 5 elements
auto end = original.cbegin();
std::advance(end, 5);
// Construct sublist from iterator range
std::list<int> sublist(begin, end);
// Print new list
for (auto&& e : sublist)
std::cout << e << ' '; // prints "3 4 5"
}