The answer to the question on stackoverflow: http://stackoverflow.com/questions/20721594/how-to-extract-a-list-from-a-linked-list-in-c/

gistfile1.cpp

#include <iostream>
#include <string>

using namespace std;

template <typename T>
struct Node
{
    T data;
    Node* next;
};

template <typename T>
void showList(const Node<T>* head)
{
    while(head != NULL)
    {
        cout << head->data << " ";
        head = head->next;
    }
    cout << endl;
}

template <typename T>
void pushToList(Node<T>*& head, const T &element)
{
    Node<T> *p = new Node<T>;
    p->data = element;
    p->next = head;
    head = p;
}

template <typename T>
T popFromList(Node<T>*& head)
{
    T value;

    if (head != NULL) {
        Node<T>* tmp = head;
        value = head->data;
        head = head->next;
        delete tmp;
    }
    
    return value;
}

template <typename T>
Node<T>* arrayToList(const T tab[], size_t size)
{
    Node<T>* head = NULL;
    for(int i = size - 1; i >= 0; i--){
        pushToList(head, tab[i]);
    }
    return head;
}

template <typename T>
void reverseList(Node<T>*& head)
{
    Node<T> *result = NULL;
    while(head != NULL) {
        pushToList(result, popFromList(head));
    }
    head = result;
}

template<typename T>
Node<T>* extract(Node<T>*& head, bool (*predicate)(const T&))
{
    Node<T> *extracted = NULL;
    Node<T> *rest = NULL;

    while (head != NULL) {
        T value = popFromList(head);
        if (predicate(value)) {
            pushToList(extracted, value);
        } else {
            pushToList(rest, value);
        }
    }

    reverseList(extracted);
    reverseList(rest);

    head = rest;

    return extracted;
}

template <typename T>
void deleteList(Node<T>*& head)
{
    while (head != NULL) {
        popFromList(head);
    }
}

bool isEven(const int& n)
{
    return n%2 == 0;
}

bool isLong(const string& s)
{
    return s.size() >=5;
}

int main(int argc, char *argv[])
{
    int xs[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    Node<int> *list = arrayToList(xs, sizeof(xs) / sizeof(xs[0]));
    Node<int> *extracted = extract(list, &isEven);

    showList(extracted);
    showList(list);

    deleteList(list);
    deleteList(extracted);

    return 0;
}