Singly Linked List Example Code

// list.cpp

#include <iostream>
#include "cmpt_error.h"

using namespace std;

struct Node {
        int val;
        Node* next;
}; // struct Node

void test1() {
        Node* head = new Node{5, nullptr};
        cout << head->val << "\n";

        Node* p = new Node{3, nullptr};
        p->next = head;
        head = p;

        cout << head->val << " ";
        cout << head->next->val << "\n";

        delete head->next;
        delete head;
}

// Note that is essential that head be passed by reference here, i.e. using
// the &. That's because the value of head is being modified.
void push(int x, Node*& head) {
        head = new Node{x, head};
}

// Note that is essential that head be passed by reference here, i.e. using
// the &. That's because the value of head is being modified.
int pop(Node*& head) {
        if (head == nullptr) cmpt::error("can't pop empty list");
        Node* p = head;
        head = head->next;
        int result = p->val;
        delete p;
        return result;
}

void clear(Node*& head) {
        while (head != nullptr) {
                Node* p = head;
                head = head->next;
                delete p;
        }
}

void test2() {
        Node* head = nullptr;

        for(int i = 0; i < 100; ++i) push(i, head);

        cout << head->val << " ";
        cout << head->next->val << "\n";

        // print the list
        for(Node* p = head; p != nullptr; p = p->next) {
                cout << p->val << " ";
        }

        // Node* p = head;
        // while (p != nullptr) {
        //      cout << p->val << " ";
        //      p = p->next;
        // }

        // delete all the elements from the list
        // while (head != nullptr) {
        //      cout << pop(head) << " popped\n";
        // }

        clear(head);
}

int main() {
        // test1();
        test2();
}