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Program to implement Singly Linked List in C++ using class

  • Difficulty Level : Basic
  • Last Updated : 22 Jul, 2021

The linked list stores data in sequential storage, like arrays. Though the data are stored sequentially, the memory locations are not contiguous.
Unlike an array, the linked list can store data of different data types.
The below diagram represents the linked-list structure.
 

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In C++ the linked list can be represented with a class and a Node class separately, which has two members, namely data and a next pointer which points to the next node. 



InsertNode: In this article, insertion is done at the end of the list. Follow the steps to insert a node in the linked list.

DeleteNode: In this article, deletion is done using the index of the node. Follow the steps to delete a node: 

Below is the implementation of the above approach:

C++




// C++ program for the above approach
#include <iostream>
using namespace std;
  
// Node class to represent
// a node of the linked list.
class Node {
public:
    int data;
    Node* next;
  
    // Default constructor
    Node()
    {
        data = 0;
        next = NULL;
    }
  
    // Parameterised Constructor
    Node(int data)
    {
        this->data = data;
        this->next = NULL;
    }
};
  
// Linked list class to
// implement a linked list.
class Linkedlist {
    Node* head;
  
public:
    // Default constructor
    Linkedlist() { head = NULL; }
  
    // Function to insert a
    // node at the end of the
    // linked list.
    void insertNode(int);
  
    // Function to print the
    // linked list.
    void printList();
  
    // Function to delete the
    // node at given position
    void deleteNode(int);
};
  
// Function to delete the
// node at given position
void Linkedlist::deleteNode(int nodeOffset)
{
    Node *temp1 = head, *temp2 = NULL;
    int ListLen = 0;
  
    if (head == NULL) {
        cout << "List empty." << endl;
        return;
    }
  
    // Find length of the linked-list.
    while (temp1 != NULL) {
        temp1 = temp1->next;
        ListLen++;
    }
  
    // Check if the position to be
    // deleted is less than the length
    // of the linked list.
    if (ListLen < nodeOffset) {
        cout << "Index out of range"
             << endl;
        return;
    }
  
    // Declare temp1
    temp1 = head;
  
    // Deleting the head.
    if (nodeOffset == 1) {
  
        // Update head
        head = head->next;
        delete temp1;
        return;
    }
  
    // Traverse the list to
    // find the node to be deleted.
    while (nodeOffset-- > 1) {
  
        // Update temp2
        temp2 = temp1;
  
        // Update temp1
        temp1 = temp1->next;
    }
  
    // Change the next pointer
    // of the previous node.
    temp2->next = temp1->next;
  
    // Delete the node
    delete temp1;
}
  
// Function to insert a new node.
void Linkedlist::insertNode(int data)
{
    // Create the new Node.
    Node* newNode = new Node(data);
  
    // Assign to head
    if (head == NULL) {
        head = newNode;
        return;
    }
  
    // Traverse till end of list
    Node* temp = head;
    while (temp->next != NULL) {
  
        // Update temp
        temp = temp->next;
    }
  
    // Insert at the last.
    temp->next = newNode;
}
  
// Function to print the
// nodes of the linked list.
void Linkedlist::printList()
{
    Node* temp = head;
  
    // Check for empty list.
    if (head == NULL) {
        cout << "List empty" << endl;
        return;
    }
  
    // Traverse the list.
    while (temp != NULL) {
        cout << temp->data << " ";
        temp = temp->next;
    }
}
  
// Driver Code
int main()
{
    Linkedlist list;
  
    // Inserting nodes
    list.insertNode(1);
    list.insertNode(2);
    list.insertNode(3);
    list.insertNode(4);
  
    cout << "Elements of the list are: ";
  
    // Print the list
    list.printList();
    cout << endl;
  
    // Delete node at position 2.
    list.deleteNode(2);
  
    cout << "Elements of the list are: ";
    list.printList();
    cout << endl;
    return 0;
}
Output
Elements of the list are: 1 2 3 4 
Elements of the list are: 1 3 4 

Time Complexity: O(N)
Auxiliary Space: O(N)




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