# Program to Insert a New Node at the End of Doubly Linked List

Program to Insert a New Node at the End of Doubly Linked List on fibonacci, factorial, prime, armstrong, swap, reverse, search, sort, stack, queue, array, linkedlist, tree, graph etc.

## Q. Program to insert a new node at the end of doubly linked list.

### Explanation

In this program, we will create a doubly linked list and insert every new node at the end of the list. If the list is empty, then head and tail will point to newly added node. If list is not empty then, insert the new node at the end of the list such that tail's next will point to new node. Make new node as new tail of the list and its next will point to null.

In above example, node 4 was the tail of the list. Now, the new node will be inserted at the end of the list such that node 4's next will point to new node. Make new node as the tail of the list, and its next will point to null.

### Algorithm

1. Define a Node class which represents a node in the list. It will have three properties: data, previous which will point to the previous node and next which will point to the next node.
2. Define another class for creating a doubly linked list, and it has two nodes: head and tail. Initially, head and tail will point to null.
1. It first checks whether the head is null, then it will insert the node as the head.
2. Both head and tail will point to a newly added node.
3. Head's previous pointer will point to null and tail's next pointer will point to null.
4. If the head is not null, the new node will be inserted at the end of the list such that new node's previous pointer will point to tail.
5. The new node will become the new tail. Tail's next pointer will point to null.
4. display() will show all the nodes present in the list.
1. Define a new node 'current' that will point to the head.
2. Print current.data till current points to null.
3. Current will point to the next node in the list in each iteration.

## Solution

### Python

```#Represent a node of doubly linked list
class Node:
def __init__(self,data):
self.data = data;
self.previous = None;
self.next = None;

class InsertEnd:
def __init__(self):
self.tail = None;

#Create a new node
newNode = Node(data);

#If list is empty
#Both head and tail will point to newNode
#head's previous will point to None
#tail's next will point to None, as it is the last node of the list
self.tail.next = None;
#Add newNode as new tail of the list
else:
#newNode will be added after tail such that tail's next will point to newNode
self.tail.next = newNode;
#newNode's previous will point to tail
newNode.previous = self.tail;
#newNode will become new tail
self.tail = newNode;
#As it is last node, tail's next will point to None
self.tail.next = None;

#display() will print out the nodes of the list
def display(self):
#Node current will point to head
print("List is empty");
return;
print("Adding a node to the end of the list: ");
while(current != None):
#Prints each node by incrementing pointer.
print(current.data),
current = current.next;

print();

dList = InsertEnd();

dList.display();
dList.display();
dList.display();
dList.display();
dList.display();
```

Output:

```Adding a node to the end of the list:
1
Adding a node to the end of the list:
1 2
Adding a node to the end of the list:
1 2 3
Adding a node to the end of the list:
1 2 3 4
Adding a node to the end of the list:
1 2 3 4 5
```

### C

```#include <stdio.h>

//Represent a node of the doubly linked list

struct node{
int data;
struct node *previous;
struct node *next;
};

struct node *head, *tail = NULL;

//Create a new node
struct node *newNode = (struct node*)malloc(sizeof(struct node));
newNode->data = data;

//If list is empty
//Both head and tail will point to newNode
//head's previous will point to NULL
//tail's next will point to NULL, as it is the last node of the list
tail->next = NULL;
}
//Add newNode as new tail of the list
else {
//newNode will be added after tail such that tail's next will point to newNode
tail->next = newNode;
//newNode's previous will point to tail
newNode->previous = tail;
//newNode will become new tail
tail = newNode;
//As it is last node, tail's next will point to NULL
tail->next = NULL;
}
}

//display() will print out the nodes of the list
void display() {
//Node current will point to head
printf("List is empty\n");
return;
}
printf("Adding a node to the end of the list: \n");
while(current != NULL) {
//Prints each node by incrementing pointer.
printf("%d ", current->data);
current = current->next;
}
printf("\n");
}

int main()
{
display();
display();
display();
display();
display();

return 0;
}
```

Output:

```Adding a node to the end of the list:
1
Adding a node to the end of the list:
1 2
Adding a node to the end of the list:
1 2 3
Adding a node to the end of the list:
1 2 3 4
Adding a node to the end of the list:
1 2 3 4 5
```

### JAVA

```public class InsertEnd {

//Represent a node of the doubly linked list

class Node{
int data;
Node previous;
Node next;

public Node(int data) {
this.data = data;
}
}

//Create a new node
Node newNode = new Node(data);

//If list is empty
//Both head and tail will point to newNode
//head's previous will point to null
//tail's next will point to null, as it is the last node of the list
tail.next = null;
}
//Add newNode as new tail of the list
else {
//newNode will be added after tail such that tail's next will point to newNode
tail.next = newNode;
//newNode's previous will point to tail
newNode.previous = tail;
//newNode will become new tail
tail = newNode;
//As it is last node, tail's next will point to null
tail.next = null;
}
}

//display() will print out the nodes of the list
public void display() {
//Node current will point to head
System.out.println("List is empty");
return;
}
System.out.println("Adding a node to the end of the list: ");
while(current != null) {
//Prints each node by incrementing the pointer.

System.out.print(current.data + " ");
current = current.next;
}
System.out.println();
}

public static void main(String[] args) {

InsertEnd dList = new InsertEnd();

dList.display();
dList.display();
dList.display();
dList.display();
dList.display();
}
}
```

Output:

```Adding a node to the end of the list:
1
Adding a node to the end of the list:
1 2
Adding a node to the end of the list:
1 2 3
Adding a node to the end of the list:
1 2 3 4
Adding a node to the end of the list:
1 2 3 4 5
```

### C#

```using System;
{
public class Program
{
//Represent a node of the doubly linked list

public class Node<T>{
public T data;
public Node<T> previous;
public Node<T> next;

public Node(T value) {
data = value;
}
}

public class InsertEnd<T>{
protected Node<T> tail = null;

//Create a new node
Node<T> newNode = new Node<T>(data);

//If list is empty
//Both head and tail will point to newNode
//head's previous will point to null
//tail's next will point to null, as it is the last node of the list
tail.next = null;
}
//Add newNode as new tail of the list
else {
//newNode will be added after tail such that tail's next will point to newNode
tail.next = newNode;
//newNode's previous will point to tail
newNode.previous = tail;
//newNode will become new tail
tail = newNode;
//As it is last node, tail's next will point to null
tail.next = null;
}
}

//display() will print out the nodes of the list
public void display() {
//Node current will point to head
Console.WriteLine("List is empty");
return;
}
Console.WriteLine("Adding a node to the end of the list: ");
while(current != null) {
//Prints each node by incrementing the pointer.

Console.Write(current.data + " ");
current = current.next;
}
Console.WriteLine();
}
}

public static void Main()
{
InsertEnd<int> dList = new InsertEnd<int>();

dList.display();
dList.display();
dList.display();
dList.display();
dList.display();
}
}
}
```

Output:

```Adding a node to the end of the list:
1
Adding a node to the end of the list:
1 2
Adding a node to the end of the list:
1 2 3
Adding a node to the end of the list:
1 2 3 4
Adding a node to the end of the list:
1 2 3 4 5
```

### PHP

```<!DOCTYPE html>
<html>
<body>
<?php
//Represent a node of doubly linked list
class Node{
public \$data;
public \$previous;
public \$next;

function __construct(\$data){
\$this->data = \$data;
}
}
class InsertEnd{
public \$tail;
function __construct(){
\$this->tail = NULL;
}

//Create a new node
\$newNode = new Node(\$data);

//If list is empty
//Both head and tail will point to newNode
//head's previous will point to NULL
//tail's next will point to NULL, as it is the last node of the list
\$this->tail->next = NULL;
}
//Add newNode as new tail of the list
else {
//newNode will be added after tail such that tail's next will point to newNode
\$this->tail->next = \$newNode;
//newNode's previous will point to tail
\$newNode->previous = \$this->tail;
//newNode will become new tail
\$this->tail = \$newNode;
//As it is last node, tail's next will point to NULL
\$this->tail->next = NULL;
}
}

//display() will print out the nodes of the list
function display() {
//Node current will point to head
print("List is empty <br>");
return;
}
print("Adding a node to the end of the list: <br>");
while(\$current != NULL) {
//Prints each node by incrementing pointer.
print(\$current->data . " ");
\$current = \$current->next;
}
print("<br>");
}
}

\$dList = new InsertEnd();

\$dList->display();
\$dList->display();
\$dList->display();
\$dList->display();
\$dList->display();
?>
</body>
</html>
```

Output:

```Adding a node to the end of the list:
1
Adding a node to the end of the list:
1 2
Adding a node to the end of the list:
1 2 3
Adding a node to the end of the list:
1 2 3 4
Adding a node to the end of the list:
1 2 3 4 5
```

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