C++ Linked List Exercises: Insert a new node at the end of a Doubly Linked List

C++ Linked List: Exercise-19 with Solution

Write a C++ program to insert a new node at the end of a Doubly Linked List.

Test Data:
Doubly linked list is as follows:
------------------------------
Traversal in Forward direction: Orange White Green Red
Traversal in Reverse direction: Red Green White Orange
Insert a new node at the end of a Doubly Linked List:
-------------------------------------------------------------
Traversal in Forward direction: Orange White Green Red Pink
Traversal in Reverse direction: Pink Red Green White Orange

Sample Solution:

C++ Code:

#include <iostream> // Including input-output stream header file

using namespace std; // Using standard namespace

// A doubly linked list node
struct Node {
   string data; // Data field to store string data
   struct Node* next; // Pointer to the next node
   struct Node* prev; // Pointer to the previous node
};

// Function to append data at the front of the doubly linked list
void append_data(Node** head, string new_data)
{
   // Create a new node and allocate memory.
   struct Node* newNode = new Node;

   // Assign data to the new node
   newNode->data = new_data;

   // A new node has been added with the name head and the previous node 
   // set to null, since it is being added at the front.
   newNode->next = (*head);
   newNode->prev = NULL;

   // Previous head is the new node
   if ((*head) != NULL)
   (*head)->prev = newNode;

   // Head points to the new node
   (*head) = newNode;
} 

// Function to insert a new node at the end of the doubly linked list
void insert_Node_at_end(Node** head, string color)
{
    Node* new_node = new Node();
    Node* last_node = *head;  
    new_node->data = color;
    new_node->next = NULL;
    if (*head == NULL) {
        new_node->prev = NULL;
        *head = new_node;
        return;
    }
    while (last_node->next != NULL)
        last_node = last_node->next;
    last_node->next = new_node;
    new_node->prev = last_node;
    return;
}

// Following function displays contents of the doubly linked list
void displayDlList(Node* head)
{
    Node* last_node;
    cout << "\nTraversal in Forward direction: ";
    while (head != NULL) {
        cout << " " << head->data << " "; // Displaying data in forward direction
        last_node = head;
        head = head->next;
    }
    cout << "\nTraversal in Reverse direction: ";
    while (last_node != NULL) {
        cout << " " << last_node->data << " "; // Displaying data in reverse direction
        last_node = last_node->prev;
    }
}

// Main program
int main() {
   /* Start with the empty list */
   struct Node* head = NULL; // Initializing the head of the linked list as NULL
   append_data(&head, "Red"); // Appending "Red" at the front of the list
   append_data(&head, "Green"); // Appending "Green" at the front of the list
   append_data(&head, "White"); // Appending "White" at the front of the list
   append_data(&head, "Orange"); // Appending "Orange" at the front of the list  
   cout<<"Doubly linked list is as follows: ";
   cout<<"\n------------------------------";
   displayDlList(head); // Displaying the doubly linked list
   cout<<"\n\nInsert a new node at the end of a Doubly Linked List:";
   cout<<"\n-------------------------------------------------------------";
   insert_Node_at_end(&head, "Pink"); // Inserting "Pink" node at the end of the list
   displayDlList(head); // Displaying the updated doubly linked list
   cout<<endl;
   return 0; // Returning from the main function
}

Sample Output:

Doubly linked list is as follows:
------------------------------
Traversal in Forward direction:  Orange  White  Green  Red
Traversal in Reverse direction:  Red  Green  White  Orange

Insert a new node at the end of a Doubly Linked List:
-------------------------------------------------------------
Traversal in Forward direction:  Orange  White  Green  Red  Pink
Traversal in Reverse direction:  Pink  Red  Green  White  Orange

Flowchart:

CPP Code Editor:

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