Singly Linked List in C++

October 7, 2025

What is a singly linked list in C++ programming?

Singly linked list in C++ is one of the simplest data structure. Since, we can dynamically add or delete items as per requirement, while in Arrays the size of the array once defined can not be altered.

Let us learn more about the singly linked lists in C++ programming in this article.

What is Singly Linked List in C++

A Singly linked List a Sequence of nodes connected to one another using pointers. Following are components of Singly Linked List –

Data – The value held
Next Pointer – Contains the address of the next node in the sequence

Unlike an array that is contiguous each node in a Singly Linked List is scattered all over memory and are connected to one another using pointers.

Important The size of an array can not be increased once declared, but since Linked List memory are created dynamically (see below) and they need not be in a contiguous format and are connected with pointers. We can add or delete as many items from a Linked List in realtime.

Linked List in C++

Insertion in Singly Linked List

Insertion at beginning in singly Linked List

Insertion at n^th position in singly Linked List

Insertion at end in singly Linked List

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Structure of the singly linked list

The following set of code is used to struct the nodes of a singly linked list. Here we have defined a singly linked list that will store integer type data in it.

Using Class

Using Struct

Using Class

class node 
{   
    int data;  
    node *next;  
};

Using Struct

struct Node
{
  int data;
  struct Node *next;
};

This code will create a data type Node, which will be able to store two values-:

int value – data
pointer value – address of the next node

Operations on singly linked list

Following operations can be performed over a singly linked list

Insertion of a node

Using Class

Using Struct

Using Class

void insertStart(int data)
    {
        Node* newNode = new Node(data);
        newNode->next = head;
        head = newNode;
        cout << data << " Inserted" << endl;
    }

Using Struct

void insertStart(Node** head, int data)
{
  Node* newNode = new Node;
  newNode->data = data;
  newNode->next = *head;

  *head = newNode;
  cout << "\n" << newNode->data << " Inserted" << endl;
}

Deletion of a node

Using Class

Using Struct

Using Class

void deleteStart()
    {
        if (head == nullptr)
        {
            cout << "Linked List Empty, nothing to delete" << endl;
            return;
        }

        Node* temp = head;
        head = head->next;

        cout << temp->data << " deleted" << endl;
        delete temp;
    }

Using Struct

void deleteStart(Node** head)
{
  Node* temp = *head;

  if (*head == nullptr)
  {
    cout << "Linked List Empty, nothing to delete" << endl;
    return;
  }

  *head = (*head)->next;

  cout << "\n" << temp->data << " deleted" << endl;
  delete temp;
}

Traversal in a Singly Linked List

Using Class

Using Struct

Using Class

 void display()
    {
        cout << "Linked List: ";

        Node* current = head;
        while (current != nullptr)
        {
            cout << current->data << " ";
            current = current->next;
        }

        cout << endl;
    }

Using Struct

void display(Node* node)
{
  cout << "\nLinked List: ";

  while (node != nullptr)
  {
    cout << node->data << " ";
    node = node->next;
  }
  cout << endl;
}

Code for Implementing Single Linked List in C++

Using Class

Using Struct

Using Class

Run

#include <iostream>

using namespace std;

class Node
{
public:
    int data;
    Node* next;

    Node(int value) : data(value), next(nullptr) {}
};

class LinkedList
{
private:
    Node* head;

public:
    LinkedList() : head(nullptr) {}

    void insertStart(int data)
    {
        Node* newNode = new Node(data);
        newNode->next = head;
        head = newNode;
        cout << data << " Inserted" << endl;
    }

    void deleteStart()
    {
        if (head == nullptr)
        {
            cout << "Linked List Empty, nothing to delete" << endl;
            return;
        }

        Node* temp = head;
        head = head->next;

        cout << temp->data << " deleted" << endl;
        delete temp;
    }

    void display()
    {
        cout << "Linked List: ";

        Node* current = head;
        while (current != nullptr)
        {
            cout << current->data << " ";
            current = current->next;
        }

        cout << endl;
    }
};

int main()
{
    LinkedList list;

    list.insertStart(100);
    list.insertStart(80);
    list.insertStart(60);
    list.insertStart(40);
    list.insertStart(20);

    list.display();

    list.deleteStart();
    list.deleteStart();

    list.display();

    return 0;
}

Output

100 Inserted
80 Inserted
60 Inserted
40 Inserted
20 Inserted
Linked List: 20 40 60 80 100 
20 deleted
40 deleted
Linked List: 60 80 100

Using Struct

Run

 #include <iostream>

using namespace std;

struct Node
{
  int data;
  Node* next;
};

void insertStart(Node** head, int data)
{
  Node* newNode = new Node;
  newNode->data = data;
  newNode->next = *head;

  *head = newNode;
  cout << "\n" << newNode->data << " Inserted" << endl;
}

void deleteStart(Node** head)
{
  Node* temp = *head;

  if (*head == nullptr)
  {
    cout << "Linked List Empty, nothing to delete" << endl;
    return;
  }

  *head = (*head)->next;

  cout << "\n" << temp->data << " deleted" << endl;
  delete temp;
}

void display(Node* node)
{
  cout << "\nLinked List: ";

  while (node != nullptr)
  {
    cout << node->data << " ";
    node = node->next;
  }
  cout << endl;
}

int main()
{
  Node* head = nullptr;

  insertStart(&head, 100);
  insertStart(&head, 80);
  insertStart(&head, 60);
  insertStart(&head, 40);
  insertStart(&head, 20);

  display(head);

  deleteStart(&head);
  deleteStart(&head);
  display(head);

  return 0;
}

Output

100 Inserted

80 Inserted

60 Inserted

40 Inserted

20 Inserted

Linked List: 20 40 60 80 100 

20 deleted

40 deleted

Linked List: 60 80 100

Time and Space Complexity:

Operation	Class-based Implementation	Structure-based Implementation	Time Complexity	Space Complexity
Insert at Start	`insertStart()` method in class	`insertStart()` function with pointer	O(1)	O(1)
Delete from Start	`deleteStart()` method in class	`deleteStart()` function with pointer	O(1)	O(1)
Display Linked List	`display()` method in class	`display()` function	O(n)	O(1)
Overall Program (Insertion + Deletion + Display)	Uses OOP (encapsulation, constructor)	Uses procedural approach (struct & pointers)	O(n)	O(n)

Disadvantages of singly linked list in CPP programming

Members could be assigned anywhere in the memory.
Each member shall include an address size member, hence it utilizes poor memory.
Some operations like reversing a list is complicated when compared with arrays,

Why Singly Linked List?

Performing operations on a list becomes easy

Singly linked list give us the flexibility to perform various operations such as insertion, deletion in an efficient manner as compared to arrays.

Efficient memory allocation

We need not tho allocate memory in advance to the singly linked list, dynamic memory is allocated in singly linked list hence it saves extra memory .

Implentation of advance data structure

Many advance data structures are implemented with the help of singly linked list hence they become very useful there.

To Wrap It Up:

In essence, a singly linked list in C++ offers a flexible, dynamic structure where nodes can be added or removed easily, unlike static arrays. Basic operations such as insertion at the beginning, traversal, and deletion are straightforward, though random access and some more complex manipulations can become inefficient.

Despite its limitations in memory overhead and complexity for certain tasks (e.g. reversing or random access), the singly linked list remains a foundational tool. It underpins many advanced data structures and is ideal when frequent insertions or deletions are required.

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FAQs

What are the main advantages of using a Singly Linked List in C++?

Singly linked lists offer flexibility in memory usage and make insertion or deletion efficient, especially when the size of data changes frequently during execution.

What are the drawbacks of a Singly Linked List?

The major drawbacks include no backward traversal and higher memory usage due to pointer storage. Also, random access to elements is not possible, unlike arrays.

How do you detect a loop in a Singly Linked List?

A loop in a singly linked list can be detected using Floyd’s Cycle Detection Algorithm (Tortoise and Hare method), which uses two pointers moving at different speeds.

What happens if you try to delete a node without having access to the head pointer?

If the head pointer is not available, you can delete the node by copying data from the next node to the current one and then deleting the next node, except for the last node.

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