const function modifying data in Doubly Linked List - c++

I have created a doubly linked list.
in the list, there is a function that is const, and is not supposed to modify the object. but it is modifyind I dont know why.
#include<iostream>
using namespace std;
class Node {
public:
int data;
Node* prev;
Node* next;
Node(int val) :data(val), next(NULL), prev(NULL) {}
};
class List {
Node* head;
Node* tail;
public:
List() :head(NULL), tail(NULL) {}
void addToTail(int val) {
Node* temp = new Node(val);
if (head == NULL) {
head = temp;
tail = temp;
}
else {
tail = head;
while (tail->next != NULL) {
tail = tail->next;
}
tail->next = temp;
temp->prev = tail;
tail = temp;
}
}
int search(int val) const
{
if (head->data == val)
head->data = 12;
return head->data;
}
};
int main()
{
List l;
l.addToTail(1);
l.addToTail(2);
l.addToTail(3);
l.addToTail(4);
l.addToTail(5);
int c = l.search(1);
//c = 102;
cout << c;
}
Now I have tried to use const before the return type, but obviously it doesnt matter. it does not affect the result;
in the search(int val) function, I am sending a value to check if 'head->data' is equal to the 'val', it should not modify the 'head->data = 12' because the function is const. but it is doing this.

The const qualifier for the member function only tells the compiler that you won't modify this object.
And you don't do that: You modify head->data which is another object.
It would be a different issue if you tried to reassign the variables head or tail.

Related

Linked List insertion isn't working in for/while loop

I am learning DSA, and was trying to implement linked list but the insertion function that i wrote is not
working in a for or while loop, its not the same when i call that function outside the loop, it works that way. I am not able to figure it out, please someone help me.
#include <iostream>
class Node {
public:
int data;
Node *next;
Node(int &num) {
this->data = num;
next = NULL;
}
};
class LinkedList {
Node *head = NULL;
public:
void insert(int num) {
Node *tmp;
if (head == NULL) {
head = new Node(num);
tmp = head;
} else {
tmp->next = new Node(num);
tmp = tmp->next;
}
}
void printList() {
Node *tmp = head;
while (tmp) {
std::cout << tmp->data << " ";
tmp = tmp->next;
}
std::cout << std::endl;
}
void reverseList() {
Node *curr = head, *prev = NULL, *nextNode;
while (curr) {
nextNode = curr->next;
curr->next = prev;
prev = curr;
curr = nextNode;
}
head = prev;
}
};
int main() {
LinkedList list1;
// This is not working
int num;
while (num != -1) {
std::cin >> num;
list1.insert(num);
}
// This is working
// list1.insert(1);
// list1.insert(2);
// list1.insert(3);
// list1.insert(4);
// list1.insert(5);
list1.printList();
list1.reverseList();
list1.printList();
return 0;
}
I expect this after insertion
Edit:
although #Roberto Montalti solved this for me, but before that I tried passing incrementing value using a for loop which worked but as soon as I pull that cin out it crashes. can someone tell me what's happening under the hood?
for (int i = 1; i <= 10; i++)
{
list1.insert(i);
}
When inserting the nth item (1st excluded) tmp is a null pointer, i don't understand what you are doing there, you are assigning to next of some memory then you make that pointer point to another location, losing the pointer next you assigned before, you must keep track of the last item if you want optimal insertion. This way you are only assigning to some *tmp then going out of scope loses all your data... The best way is to just keep a pointer to the last inserted item, no need to use *tmp.
class LinkedList
{
Node *head = NULL;
Node *tail = NULL;
public:
void insert(int num)
{
if (head == NULL)
{
head = new Node(num);
tail = head;
}
else
{
tail->next = new Node(num);
tail = tail->next;
}
}
...
}
You need to loop until you reach the end of the list and then add the new node after that. Like this.
void insert(int num) {
Node *tmp = head;
if (head == NULL) {
head = new Node(num);
}
else {
while (tmp->next != NULL) {
tmp = tmp->next;
}
tmp->next = new Node(num);
}
}
first of all you need to define a node for each of the tail and head of the list as follows
Node *h;
Node *t;
you may also separate the Node from the LinkedList class so you can modify easily
class Node{
public:
int data;
Node *next;
Node(int data, Node* next);
~Node();
};
Node::Node(int data, Node* next)
{
this->data= data;
this->next= next;
}
Node::~Node(){}
}
after that you can try to add these functions to your LinkedList class
so it can deal with other special cases such empty list or full, etc..
void addToHead(int data){
Node *x = new Node(data,h);
h=x;
if(t==NULL){
t=x;
}
void addToTail(int data){
Node *x = new Node(data,NULL);
if(isEmpty()){
h=t=x;
}
else
{
t->next=x;
t=x;
}
}
now for the insert function try this after you implemented the Node class and the other functions,
void insert(int v){
if(h==nullptr){addToHead(v); return;}
if(h->data>=v) {addToHead(v);return;}
if(t->data<=v) {addToTail(v); return;}
// In this case there is at least two nodes
Node *k=h->next;
Node *p=h;
while(k != nullptr){
if(k->data >v){
Node *z =new Node(v,k);
p->next=z;
return;
}
p=k;
k=k->next;
}
}
the idea of making all of this is not lose the pointer when it goes through elements in the Linked List so you don't end up with a run time error.
I hope this can be useful to you.
There was an issue with your insert function.
Read about segmentation fault here https://www.geeksforgeeks.org/core-dump-segmentation-fault-c-cpp/#:~:text=Core%20Dump%2FSegmentation%20fault%20is,is%20known%20as%20core%20dump.
for a quick workaround you can use this
using namespace std;
#include <iostream>
class Node
{
public:
int data;
Node *next;
Node(int num)
{
this->data = num;
next = NULL;
}
};
class LinkedList
{
Node *head = NULL;
public:
void insert(int num)
{
Node *tmp= new Node(num);
tmp->next=head;
head=tmp;
}
void printList()
{
Node *tmp = head;
while (tmp)
{
std::cout << tmp->data << " ";
tmp = tmp->next;
}
std::cout << std::endl;
}
void reverseList()
{
Node *curr = head, *prev = NULL, *nextNode;
while (curr)
{
nextNode = curr->next;
curr->next = prev;
prev = curr;
curr = nextNode;
}
head = prev;
}
};
int main()
{
LinkedList list1;
// This is not working
int num,i=0,n;
cout<<"Type the value of n";
cin>>n;
while (i<n)
{
cin >> num;
cout<<num<<" "<<&num<<endl;
list1.insert(num);
i++;
}
list1.printList();
list1.reverseList();
list1.printList();
return 0;
}

C++ Linked List HEAD keeps resetting to NULL

I need help in understanding why my Linked List approach doesn't work as expected.
#include <iostream>
using namespace std;
class Node {
public:
int Data;
Node* Next;
Node(int data) {
Data = data;
Next = NULL;
}
};
void insertNodeAtEnd(Node* HEAD, int data) {
Node* it = HEAD;
if (HEAD == NULL) { HEAD = new Node(data); }
else {
while (it->Next != NULL) { it = it -> Next; }
it -> Next = new Node(data);
}
}
void printLinkedList(Node* HEAD) {
Node* it = HEAD;
while (it != NULL) {
cout << it->Data << endl;
it = it -> Next;
}
}
int main() {
Node* HEAD = NULL;
// Node* HEAD = new Node(0);
insertNodeAtEnd(HEAD, 5);
insertNodeAtEnd(HEAD, 2);
insertNodeAtEnd(HEAD, 10);
printLinkedList(HEAD);
return 0;
}
The above main() function does NOT work (ie: no output, and the HEAD keeps resetting to NULL as soon as the control leaves insertNodeAtEnd()), and I've found similar questions here on SO which explain that this is because the pointer is being passed by value, and that makes partial sense to me.
Why does it work as expected when I replace Node* HEAD = NULL; with Node* HEAD = new Node(0); in the main() function, if the pointer is being passed as value?
How are nodes getting added if I initialise HEAD like Node* HEAD = new Node(0);, but not in the case where HEAD = NULL initially? I was able to get it to work properly by using pointer to pointer but I can't understand why this approach doesn't work. I am sorry if I haven't explained my question properly, please let me know if any clarification is required.
The underlying issue can be reduced to this code:
void insertNodeAtEnd(Node* HEAD, int data) {
//...
if (HEAD == NULL) { HEAD = new Node(data); }
//...
}
int main() {
Node* HEAD = NULL;
insertNodeAtEnd(HEAD, 5);
//...
You seem to assume that assigning to HEAD inside insertNodeAtEnd would change the HEAD variable inside of main. This is not true. Your pointer is passed by value, so the address is copied for the function. Changing this copied variable will not change the value of HEAD inside of main.
To fix this you could pass a pointer to a pointer instead, like this:
void insertNodeAtEnd(Node** HEAD, int data) {
//...
if (*HEAD == NULL) { *HEAD = new Node(data); }
//...
}
int main() {
Node* HEAD = NULL;
insertNodeAtEnd(&HEAD, 5);
//...
This pointer to a pointer is still passed by value, however the pointer that it points to will be the same as the on from main.
The problem come from your first insertion. You change the value of head which is reset when you quit the function. You can only change the value behind the pointer, not the pointer itself.
A solution for this would be to pass a pointer of pointer. Something like: (not tested)
void insertNodeAtEnd(Node** HEAD, int data) {
if (*HEAD == NULL) { *HEAD = new Node(data); }
else {
Node* it = *HEAD;
while (it->Next != NULL) { it = it -> Next; }
it -> Next = new Node(data);
}
}
int main() {
Node* HEAD = NULL;
// Node* HEAD = new Node(0);
insertNodeAtEnd(&HEAD, 5);
return 0;
}
As you don't change the pointer of pointer but only the value behind it (the actuual pointer to head) the change will be keep once you exit the function.
The answer has already been given by #Brotcrunsher. I am posting to help you implement a better solution, that separates the concept of a list and an element of a list, that incapsulates the methods used and that frees the resources it uses, when it goes out of scope:
#include <iostream>
using namespace std;
class Node {
public:
int Data;
Node* Next;
Node(int data = 0) {
Data = data;
Next = nullptr;
}
};
class List {
public:
Node* Head = nullptr;
void Insert(int data) {
if (Head == nullptr)
Head = new Node(data);
else {
Node* ptr;
for (ptr = Head; ptr->Next != nullptr; ptr = ptr->Next)
;
ptr->Next = new Node(data);
}
}
void Print() {
for (Node* ptr = Head; ptr != nullptr; ptr = ptr->Next)
cout << ptr->Data << endl;
}
~List() {
Node* ptr = Head;
while (ptr != nullptr) {
Node* tmp = ptr;
ptr = ptr->Next;
delete tmp;
}
}
};
int main() {
List list;
list.Insert(5);
list.Insert(2);
list.Insert(10);
list.Print();
return 0;
}

Do I need to delete a dynamically allocated object in Singly Linked List?

I am currently learning Linked Lists and have implemented a singly linked list with Append and Prepend methods where I have allocated objects of type Node on heap using the 'new' operator. Do I need to deallocate the object on heap using 'delete', and if so then how do I do it ?
Here is my code:-
class List
{
private:
class Node
{
public:
int data;
Node* next;
Node()
{
data = 0;
next = NULL;
}
Node(const int& data)
{
this->data = data;
}
};
Node* head;
public:
List()
{
head = NULL;
}
void Append(const int&val);
void Prepend(const int&val);
void DisplayAll();
};
void List::Append(const int&val)
{
Node* n = new Node(val); //dynamically allocated
if (head == NULL)
{
head = n;
return;
}
Node* temp = NULL;
temp = head;
while (temp->next != NULL)
{
temp = temp->next;
}
temp->next = n;
}
void List::Prepend(const int&val)
{
Node* node = new Node(val);//dynamically allocated
if (head == NULL)
{
head = node;
return;
}
node->next = head;
head = node;
}
void List::DisplayAll()
{
Node* temp = head;
while (temp != NULL)
{
std::cout << temp->data << ' ';
temp = temp->next;
}
}
For starters this constructor
Node(const int& data)
{
this->data = data;
}
does not initialize the data member next. As a result member functions Append and Prepend have a bug
void List::Append(const int&val)
{
Node* n = new Node(val); //dynamically allocated
if (head == NULL)
{
head = n;
return;
}
//...
and
void List::Prepend(const int&val)
{
Node* node = new Node(val);//dynamically allocated
if (head == NULL)
{
head = node;
return;
}
//...
The data member next of the head node has an indeterminate value.
You could declare the class Node simpler like
struct Node
{
int data;
Node* next;
};
Node* head = nullptr;
In this case for example the function Prepend will look like
void List::Prepend( const int &val )
{
head = new Node { val, head };
}
And the constructor will look like
List() = default;
To free all allocated nodes in the list you could write two more member functions clear and the destructor that calls the function clear.
For example
#include <functional>
//...
class List
{
//...
public:
void clear()
{
while ( head ) delete std::exchange( head, head->next );
}
~List() { clear(); }
//...
Also you should at least either write a copy constructor and the copy assignment operator or define them as deleted.

Doubly linked list class

I am trying to make a double linked list. Function push(int x) should add a node to the list and make the correct link. I use:
class Node {
public:
int value;
Node* next;
Node* prev;
public:
Node() {}
void set_value(int x) { value = x; }
void set_next(Node* x) { next = x; }
void set_prev(Node* x) { prev = x; }
Node* get_next() { return next; }
Node* get_prev() { return prev; }
};
class deque {
public:
Node* head;
Node* tail;
public:
deque() { head = NULL; tail = NULL; }
void push(int x) {
Node* n = new Node();
n->set_value(x);
n->set_next(NULL);
n->set_prev(NULL);
Node* t = head; //link to the next node
if (t == NULL) {
head = n;
} else {
while (t->get_next() != NULL) {
t = t->get_next();
}
t->set_next(n);
}
}
};
As I have tested the part that connects a node to the next one works fine but I am having some troubles connecting the node to the previous one. One that comes in mind is a variation of the first one:
Node* t = tail;
if (t == NULL) {
tail = n;
} else {
while (t->get_prev() != NULL) {
t = t->get_prev();
}
t->set_prev(n);
}
But by using this, the tail node is always the current n node if only the node n is the one and only node in the queue... What should I do? thanks a lot
Drawing always helps with such data structures. What you have currently:
You correctly set t's next with: t->set_next(n);. What is missing is the arrow underneath it, and it's: n->set_prev(t).
In general, when dealing with doubly-linked lists, a call to set_next should always (most of the time) be accompanied by a call to set_prev on set_next's argument. It's because of the doubly-linked list's property:
x->next == y implies y->prev == x, and y->prev == x implies x->next == y.

Simple linked list in C++

I am about to create a linked that can insert and display until now:
struct Node {
int x;
Node *next;
};
This is my initialisation function which only will be called for the first Node:
void initNode(struct Node *head, int n){
head->x = n;
head->next = NULL;
}
To add the Node, and I think the reason why my linked list isn't working correct is in this function:
void addNode(struct Node *head, int n){
struct Node *NewNode = new Node;
NewNode-> x = n;
NewNode -> next = head;
head = NewNode;
}
My main function:
int _tmain(int argc, _TCHAR* argv[])
{
struct Node *head = new Node;
initNode(head, 5);
addNode(head, 10);
addNode(head, 20);
return 0;
}
Let me run the program as I think it works. First I initialise the head Node as a Node like this:
head = [ 5 | NULL ]
Then I add a new node with n = 10 and pass head as my argument.
NewNode = [ x | next ] where next points at head. And then I change the place where head is pointing to NewNode, since NewNode is the first Node in LinkedList now.
Why isn't this working? I would appreciate any hints that could make me move in the right direction. I think LinkedList is a bit hard to understand.
When I'm printing this, it only returns 5:
This is the most simple example I can think of in this case and is not tested. Please consider that this uses some bad practices and does not go the way you normally would go with C++ (initialize lists, separation of declaration and definition, and so on). But that are topics I can't cover here.
#include <iostream>
using namespace std;
class LinkedList{
// Struct inside the class LinkedList
// This is one node which is not needed by the caller. It is just
// for internal work.
struct Node {
int x;
Node *next;
};
// public member
public:
// constructor
LinkedList(){
head = NULL; // set head to NULL
}
// destructor
~LinkedList(){
Node *next = head;
while(next) { // iterate over all elements
Node *deleteMe = next;
next = next->next; // save pointer to the next element
delete deleteMe; // delete the current entry
}
}
// This prepends a new value at the beginning of the list
void addValue(int val){
Node *n = new Node(); // create new Node
n->x = val; // set value
n->next = head; // make the node point to the next node.
// If the list is empty, this is NULL, so the end of the list --> OK
head = n; // last but not least, make the head point at the new node.
}
// returns the first element in the list and deletes the Node.
// caution, no error-checking here!
int popValue(){
Node *n = head;
int ret = n->x;
head = head->next;
delete n;
return ret;
}
// private member
private:
Node *head; // this is the private member variable. It is just a pointer to the first Node
};
int main() {
LinkedList list;
list.addValue(5);
list.addValue(10);
list.addValue(20);
cout << list.popValue() << endl;
cout << list.popValue() << endl;
cout << list.popValue() << endl;
// because there is no error checking in popValue(), the following
// is undefined behavior. Probably the program will crash, because
// there are no more values in the list.
// cout << list.popValue() << endl;
return 0;
}
I would strongly suggest you to read a little bit about C++ and Object oriented programming. A good starting point could be this: http://www.galileocomputing.de/1278?GPP=opoo
EDIT: added a pop function and some output. As you can see the program pushes 3 values 5, 10, 20 and afterwards pops them. The order is reversed afterwards because this list works in stack mode (LIFO, Last in First out)
You should take reference of a head pointer. Otherwise the pointer modification is not visible outside of the function.
void addNode(struct Node *&head, int n){
struct Node *NewNode = new Node;
NewNode-> x = n;
NewNode -> next = head;
head = NewNode;
}
I'll join the fray. It's been too long since I've written C. Besides, there's no complete examples here anyway. The OP's code is basically C, so I went ahead and made it work with GCC.
The problems were covered before; the next pointer wasn't being advanced. That was the crux of the issue.
I also took the opportunity to make a suggested edit; instead of having two funcitons to malloc, I put it in initNode() and then used initNode() to malloc both (malloc is "the C new" if you will). I changed initNode() to return a pointer.
#include <stdlib.h>
#include <stdio.h>
// required to be declared before self-referential definition
struct Node;
struct Node {
int x;
struct Node *next;
};
struct Node* initNode( int n){
struct Node *head = malloc(sizeof(struct Node));
head->x = n;
head->next = NULL;
return head;
}
void addNode(struct Node **head, int n){
struct Node *NewNode = initNode( n );
NewNode -> next = *head;
*head = NewNode;
}
int main(int argc, char* argv[])
{
struct Node* head = initNode(5);
addNode(&head,10);
addNode(&head,20);
struct Node* cur = head;
do {
printf("Node # %p : %i\n",(void*)cur, cur->x );
} while ( ( cur = cur->next ) != NULL );
}
compilation: gcc -o ll ll.c
output:
Node # 0x9e0050 : 20
Node # 0x9e0030 : 10
Node # 0x9e0010 : 5
Below is a sample linkedlist
#include <string>
#include <iostream>
using namespace std;
template<class T>
class Node
{
public:
Node();
Node(const T& item, Node<T>* ptrnext = NULL);
T value;
Node<T> * next;
};
template<class T>
Node<T>::Node()
{
value = NULL;
next = NULL;
}
template<class T>
Node<T>::Node(const T& item, Node<T>* ptrnext = NULL)
{
this->value = item;
this->next = ptrnext;
}
template<class T>
class LinkedListClass
{
private:
Node<T> * Front;
Node<T> * Rear;
int Count;
public:
LinkedListClass();
~LinkedListClass();
void InsertFront(const T Item);
void InsertRear(const T Item);
void PrintList();
};
template<class T>
LinkedListClass<T>::LinkedListClass()
{
Front = NULL;
Rear = NULL;
}
template<class T>
void LinkedListClass<T>::InsertFront(const T Item)
{
if (Front == NULL)
{
Front = new Node<T>();
Front->value = Item;
Front->next = NULL;
Rear = new Node<T>();
Rear = Front;
}
else
{
Node<T> * newNode = new Node<T>();
newNode->value = Item;
newNode->next = Front;
Front = newNode;
}
}
template<class T>
void LinkedListClass<T>::InsertRear(const T Item)
{
if (Rear == NULL)
{
Rear = new Node<T>();
Rear->value = Item;
Rear->next = NULL;
Front = new Node<T>();
Front = Rear;
}
else
{
Node<T> * newNode = new Node<T>();
newNode->value = Item;
Rear->next = newNode;
Rear = newNode;
}
}
template<class T>
void LinkedListClass<T>::PrintList()
{
Node<T> * temp = Front;
while (temp->next != NULL)
{
cout << " " << temp->value << "";
if (temp != NULL)
{
temp = (temp->next);
}
else
{
break;
}
}
}
int main()
{
LinkedListClass<int> * LList = new LinkedListClass<int>();
LList->InsertFront(40);
LList->InsertFront(30);
LList->InsertFront(20);
LList->InsertFront(10);
LList->InsertRear(50);
LList->InsertRear(60);
LList->InsertRear(70);
LList->PrintList();
}
Both functions are wrong. First of all function initNode has a confusing name. It should be named as for example initList and should not do the task of addNode. That is, it should not add a value to the list.
In fact, there is not any sense in function initNode, because the initialization of the list can be done when the head is defined:
Node *head = nullptr;
or
Node *head = NULL;
So you can exclude function initNode from your design of the list.
Also in your code there is no need to specify the elaborated type name for the structure Node that is to specify keyword struct before name Node.
Function addNode shall change the original value of head. In your function realization you change only the copy of head passed as argument to the function.
The function could look as:
void addNode(Node **head, int n)
{
Node *NewNode = new Node {n, *head};
*head = NewNode;
}
Or if your compiler does not support the new syntax of initialization then you could write
void addNode(Node **head, int n)
{
Node *NewNode = new Node;
NewNode->x = n;
NewNode->next = *head;
*head = NewNode;
}
Or instead of using a pointer to pointer you could use a reference to pointer to Node. For example,
void addNode(Node * &head, int n)
{
Node *NewNode = new Node {n, head};
head = NewNode;
}
Or you could return an updated head from the function:
Node * addNode(Node *head, int n)
{
Node *NewNode = new Node {n, head};
head = NewNode;
return head;
}
And in main write:
head = addNode(head, 5);
The addNode function needs to be able to change head. As it's written now simply changes the local variable head (a parameter).
Changing the code to
void addNode(struct Node *& head, int n){
...
}
would solve this problem because now the head parameter is passed by reference and the called function can mutate it.
head is defined inside the main as follows.
struct Node *head = new Node;
But you are changing the head in addNode() and initNode() functions only. The changes are not reflected back on the main.
Make the declaration of the head as global and do not pass it to functions.
The functions should be as follows.
void initNode(int n){
head->x = n;
head->next = NULL;
}
void addNode(int n){
struct Node *NewNode = new Node;
NewNode-> x = n;
NewNode->next = head;
head = NewNode;
}
I think that, to make sure the indeep linkage of each node in the list, the addNode method must be like this:
void addNode(struct node *head, int n) {
if (head->Next == NULL) {
struct node *NewNode = new node;
NewNode->value = n;
NewNode->Next = NULL;
head->Next = NewNode;
}
else
addNode(head->Next, n);
}
Use:
#include<iostream>
using namespace std;
struct Node
{
int num;
Node *next;
};
Node *head = NULL;
Node *tail = NULL;
void AddnodeAtbeggining(){
Node *temp = new Node;
cout << "Enter the item";
cin >> temp->num;
temp->next = NULL;
if (head == NULL)
{
head = temp;
tail = temp;
}
else
{
temp->next = head;
head = temp;
}
}
void addnodeAtend()
{
Node *temp = new Node;
cout << "Enter the item";
cin >> temp->num;
temp->next = NULL;
if (head == NULL){
head = temp;
tail = temp;
}
else{
tail->next = temp;
tail = temp;
}
}
void displayNode()
{
cout << "\nDisplay Function\n";
Node *temp = head;
for(Node *temp = head; temp != NULL; temp = temp->next)
cout << temp->num << ",";
}
void deleteNode ()
{
for (Node *temp = head; temp != NULL; temp = temp->next)
delete head;
}
int main ()
{
AddnodeAtbeggining();
addnodeAtend();
displayNode();
deleteNode();
displayNode();
}
In a code there is a mistake:
void deleteNode ()
{
for (Node * temp = head; temp! = NULL; temp = temp-> next)
delete head;
}
It is necessary so:
for (; head != NULL; )
{
Node *temp = head;
head = temp->next;
delete temp;
}
Here is my implementation.
#include <iostream>
using namespace std;
template< class T>
struct node{
T m_data;
node* m_next_node;
node(T t_data, node* t_node) :
m_data(t_data), m_next_node(t_node){}
~node(){
std::cout << "Address :" << this << " Destroyed" << std::endl;
}
};
template<class T>
class linked_list {
public:
node<T>* m_list;
linked_list(): m_list(nullptr){}
void add_node(T t_data) {
node<T>* _new_node = new node<T>(t_data, nullptr);
_new_node->m_next_node = m_list;
m_list = _new_node;
}
void populate_nodes(node<T>* t_node) {
if (t_node != nullptr) {
std::cout << "Data =" << t_node->m_data
<< ", Address =" << t_node->m_next_node
<< std::endl;
populate_nodes(t_node->m_next_node);
}
}
void delete_nodes(node<T>* t_node) {
if (t_node != nullptr) {
delete_nodes(t_node->m_next_node);
}
delete(t_node);
}
};
int main()
{
linked_list<float>* _ll = new linked_list<float>();
_ll->add_node(1.3);
_ll->add_node(5.5);
_ll->add_node(10.1);
_ll->add_node(123);
_ll->add_node(4.5);
_ll->add_node(23.6);
_ll->add_node(2);
_ll->populate_nodes(_ll->m_list);
_ll->delete_nodes(_ll->m_list);
delete(_ll);
return 0;
}
link list by using node class and linked list class
this is just an example not the complete functionality of linklist, append function and printing a linklist is explained in the code
code :
#include<iostream>
using namespace std;
Node class
class Node{
public:
int data;
Node* next=NULL;
Node(int data)
{
this->data=data;
}
};
link list class named as ll
class ll{
public:
Node* head;
ll(Node* node)
{
this->head=node;
}
void append(int data)
{
Node* temp=this->head;
while(temp->next!=NULL)
{
temp=temp->next;
}
Node* newnode= new Node(data);
// newnode->data=data;
temp->next=newnode;
}
void print_list()
{ cout<<endl<<"printing entire link list"<<endl;
Node* temp= this->head;
while(temp->next!=NULL)
{
cout<<temp->data<<endl;
temp=temp->next;
}
cout<<temp->data<<endl;;
}
};
main function
int main()
{
cout<<"hello this is an example of link list in cpp using classes"<<endl;
ll list1(new Node(1));
list1.append(2);
list1.append(3);
list1.print_list();
}
thanks ❤❤❤
screenshot https://i.stack.imgur.com/C2D9y.jpg