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<!DOCTYPE html>

<head>

<title>Document</title>

window.dataLayer = window.dataLayer || [];

function gtag() { dataLayer.push(arguments); }

gtag('js', new Date());

gtag('config', 'G-HCERBDV76D');

</script>

</head>

<body>

<nav>

Python Tutorial

</a>

</div>

</div>

</div>

<li>

Home

</a>

</li>

<li>

Projects

</a>

</li>

<li>

Free Course

</a>

</li>

<li>

DSA

</a>

</li>

</ul>

</div>

</nav>

</div>

<h3>Page Index</h3>

<ul>

<li><a href="/dsa.html#data-structure-1" title="Data Structures (I)">Data Structures

(I)</a></li>

<li><a href="/dsa.html#data-structure-2" title="Data Structures (II)">Data Structures

(II)</a></li>

<li><a href="/dsa.html#tree-1" title="Tree based DSA (I)">Tree based DSA (I)</a></li>

<li><a href="/dsa.html#tree-2" title="Tree based DSA (II)">Tree based DSA (II)</a></li>

<li><a href="/dsa.html#graph" title="Graph Data Structures and Algorithm">Graph based

DSA</a></li>

<li><a href="/dsa.html#sorting-searching" title="Sorting and Searching">Sorting and

Searching</a></li>

<li><a href="/dsa.html#greedy-algorithm" title="Greedy Algorithms">Greedy Algorithms</a>

</li>

<li><a href="/dsa.html#dynamic-programming" title="Dynamic Programming">Dynamic

Programming</a></li>

<li><a href="/dsa.html#other-algorithms" title="Other Algorithms">Other Algorithms</a>

</li>

</ul>

</div>

<h1>Linked List Operations: Traverse, Insert and Delete</h1>

In this tutorial, you will learn different operations on a linked list. Also, you will find implementation of linked list operations in C/C++, Python and Java.

There are various linked list operations that allow us to perform different actions on linked lists. For example, the insertion operation adds a new element to the linked list.

Here's a list of basic linked list operations that we will cover in this article.

<ul><li><a href="#traverse">Traversal</a> - access each element of the linked list</li>

<li><a href="#add">Insertion</a> - adds a new element to the linked list</li>

<li><a href="#delete">Deletion</a> - removes the existing elements</li>

<li><a href="#search">Search</a> - find a node in the linked list</li>

<li><a href="#sort">Sort</a> - sort the nodes of the linked list</li>

</ul>Before you learn about linked list operations in detail, make sure to know about <a href="/dsa/linked-list.html">Linked List</a> first.

<h3>Things to Remember about Linked List</h3>

<ul><li><var>head</var> points to the first node of the linked list</li>

<li><var>next</var> pointer of the last node is <var>NULL</var>, so if the next current node is <var>NULL</var>, we have reached the end of the linked list.</li>

</ul>In all of the examples, we will assume that the linked list has three nodes <code>1 --->2 --->3</code> with node structure as below:

<pre style="max-height: 600px;"><code class="dsa hljs cpp">struct node {

int data;

struct node *next;

};</code></pre>

<hr><h2 id="traverse">Traverse a Linked List</h2>

Displaying the contents of a linked list is very simple. We keep moving the temp node to the next one and display its contents.

When <var>temp</var> is <var>NULL</var>, we know that we have reached the end of the linked list so we get out of the while loop.

<pre style="max-height: 600px;"><code class="dsa hljs cpp">struct node *temp = head;

printf("\n\nList elements are - \n");

while(temp != NULL) {

printf("%d --->",temp->data);

temp = temp->next;

}</code></pre>

The output of this program will be:

<pre><samp>List elements are -

1 --->2 --->3 ---></samp></pre>

<hr><h2 id="add">Insert Elements to a Linked List</h2>

<div class="clearfix"></div>You can add elements to either the beginning, middle or end of the linked list.

<h3>1. Insert at the beginning</h3>

<ul><li>Allocate memory for new node</li>

<li>Store data</li>

<li>Change next of new node to point to head</li>

<li>Change head to point to recently created node</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs rust">struct node *newNode;

newNode = malloc(sizeof(struct node));

newNode->data = 4;

newNode->next = head;

head = newNode;</code></pre>

<h3>2. Insert at the End</h3>

<ul><li>Allocate memory for new node</li>

<li>Store data</li>

<li>Traverse to last node</li>

<li>Change next of last node to recently created node</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs rust">struct node *newNode;

newNode = malloc(sizeof(struct node));

newNode->data = 4;

newNode->next = NULL;

struct node *temp = head;

while(temp->next != NULL){

temp = temp->next;

}

temp->next = newNode;</code></pre>

<h3>3. Insert at the Middle</h3>

<ul><li>Allocate memory and store data for new node</li>

<li>Traverse to node just before the required position of new node</li>

<li>Change next pointers to include new node in between</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs rust">struct node *newNode;

newNode = malloc(sizeof(struct node));

newNode->data = 4;

struct node *temp = head;

for(int i=2; i < position; i++) {

if(temp->next != NULL) {

temp = temp->next;

}

newNode->next = temp->next;

temp->next = newNode;</code></pre>

<hr><h2 id="delete">Delete from a Linked List</h2>

You can delete either from the beginning, end or from a particular position.

<h3>1. Delete from beginning</h3>

<ul><li>Point head to the second node</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs ini">head = head->next;</code></pre>

<h3>2. Delete from end</h3>

<ul><li>Traverse to second last element</li>

<li>Change its next pointer to null</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs php">struct node* temp = head;

while(temp->next->next!=NULL){

temp = temp->next;

}

temp->next = NULL;</code></pre>

<h3>3. Delete from middle</h3>

<ul><li>Traverse to element before the element to be deleted</li>

<li>Change next pointers to exclude the node from the chain</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs perl">for(int i=2; i< position; i++) {

if(temp->next!=NULL) {

temp = temp->next;

}

temp->next = temp->next->next;</code></pre>

<hr><h2 id="search">Search an Element on a Linked List</h2>

You can search an element on a linked list using a loop using the following steps. We are finding <code>item</code> on a linked list.

<ul><li>Make <code>head</code> as the <code>current</code> node.</li>

<li>Run a loop until the <code>current</code> node is <code>NULL</code> because the last element points to <code>NULL</code>.</li>

<li>In each iteration, check if the key of the node is equal to <code>item</code>. If it the key matches the item, return <code>true</code> otherwise return <code>false</code>.</li>

</ul><pre style="max-height: 600px;"><code class="dsa hljs rust">// Search a node

bool searchNode(struct Node** head_ref, int key) {

struct Node* current = *head_ref;

while (current != NULL) {

if (current->data == key) return true;

current = current->next;

}

return false;

}</code></pre>

<hr><h2 id="sort">Sort Elements of a Linked List</h2>

We will use a simple sorting algorithm, <a href="/dsa/bubble-sort.html">Bubble Sort</a>, to sort the elements of a linked list in ascending order below.

<ol><li>Make the <code>head</code> as the <code>current</code> node and create another node <code>index</code> for later use.</li>

<li>If <code>head</code> is null, return.</li>

<li>In each iteration, follow the following step 5-6.</li>

<li>Store the next node of <code>current</code> in <code>index</code>.</li>

<li>Check if the data of the current node is greater than the next node. If it is greater, swap <code>current</code> and <code>index</code>.</li>

</ol>Check the article on <a href="/dsa/bubble-sort.html">bubble sort</a> for better understanding of its working.

<pre style="max-height: 600px;"><code class="dsa hljs php">// Sort the linked list

void sortLinkedList(struct Node** head_ref) {

struct Node *current = *head_ref, *index = NULL;

int temp;

if (head_ref == NULL) {

return;

} else {

while (current != NULL) {

// index points to the node next to current

index = current->next;

while (index != NULL) {

if (current->data > index->data) {

temp = current->data;

current->data = index->data;

index->data = temp;

}

index = index->next;

}

current = current->next;

}

}</code></pre>

<hr><h2 id="operations">LinkedList Operations in Python, Java, C, and C++</h2>

<div id="py1" onclick="changepy()" class="tabbed-editor__node tabbed-editor__node--active"><a href="#python-code">Python</a></div>

</div>

<div class="pre-code-wrapper"><div title="Click to copy" class="copy-code-button"></div><pre class="exec" style="max-height: 600px;"><code class="python hljs"># Linked list operations in Python

# Create a node

class Node:

def __init__(self, data):

self.data = data

self.next = None

class LinkedList:

def __init__(self):

self.head = None

# Insert at the beginning

def insertAtBeginning(self, new_data):

new_node = Node(new_data)

new_node.next = self.head

self.head = new_node

# Insert after a node

def insertAfter(self, prev_node, new_data):

if prev_node is None:

print("The given previous node must inLinkedList.")

return

new_node = Node(new_data)

new_node.next = prev_node.next

prev_node.next = new_node

# Insert at the end

def insertAtEnd(self, new_data):

new_node = Node(new_data)

if self.head is None:

self.head = new_node

return

last = self.head

while (last.next):

last = last.next

last.next = new_node

# Deleting a node

def deleteNode(self, position):

if self.head is None:

return

temp = self.head

if position == 0:

self.head = temp.next

temp = None

return

# Find the key to be deleted

for i in range(position - 1):

temp = temp.next

if temp is None:

break

# If the key is not present

if temp is None:

return

if temp.next is None:

return

next = temp.next.next

temp.next = None

temp.next = next

# Search an element

def search(self, key):

current = self.head

while current is not None:

if current.data == key:

return True

current = current.next

return False

# Sort the linked list

def sortLinkedList(self, head):

current = head

index = Node(None)

if head is None:

return

else:

while current is not None:

# index points to the node next to current

index = current.next

while index is not None:

if current.data > index.data:

current.data, index.data = index.data, current.data

index = index.next

current = current.next

# Print the linked list

def printList(self):

temp = self.head

while (temp):

print(str(temp.data) + " ", end="")

temp = temp.next

if __name__ == '__main__':

llist = LinkedList()

llist.insertAtEnd(1)

llist.insertAtBeginning(2)

llist.insertAtBeginning(3)

llist.insertAtEnd(4)

llist.insertAfter(llist.head.next, 5)

print('linked list:')

llist.printList()

print("\nAfter deleting an element:")

llist.deleteNode(3)

llist.printList()

print()

item_to_find = 3

if llist.search(item_to_find):

print(str(item_to_find) + " is found")

else:

print(str(item_to_find) + " is not found")

llist.sortLinkedList(llist.head)

print("Sorted List: ")

llist.printList()</code></pre></div>

</div>

<div class="pre-code-wrapper"><div title="Click to copy" class="copy-code-button"></div><pre class="exec" style="max-height: 600px;"><code class="java hljs">// Linked list operations in Java

class LinkedList {

Node head;

// Create a node

class Node {

int data;

Node next;

Node(int d) {

data = d;

next = null;

}

// Insert at the beginning

public void insertAtBeginning(int new_data) {

// insert the data

Node new_node = new Node(new_data);

new_node.next = head;

head = new_node;

}

// Insert after a node

public void insertAfter(Node prev_node, int new_data) {

if (prev_node == null) {

System.out.println("The given previous node cannot be null");

return;

}

Node new_node = new Node(new_data);

new_node.next = prev_node.next;

prev_node.next = new_node;

}

// Insert at the end

public void insertAtEnd(int new_data) {

Node new_node = new Node(new_data);

if (head == null) {

head = new Node(new_data);

return;

}

new_node.next = null;

Node last = head;

while (last.next != null)

last = last.next;

last.next = new_node;

return;

}

// Delete a node

void deleteNode(int position) {

if (head == null)

return;

Node temp = head;

if (position == 0) {

head = temp.next;

return;

}

// Find the key to be deleted

for (int i = 0; temp != null && i < position - 1; i++)

temp = temp.next;

// If the key is not present

if (temp == null || temp.next == null)

return;

// Remove the node

Node next = temp.next.next;

temp.next = next;

}

// Search a node

boolean search(Node head, int key) {

Node current = head;

while (current != null) {

if (current.data == key)

return true;

current = current.next;

}

return false;

}

// Sort the linked list

void sortLinkedList(Node head) {

Node current = head;

Node index = null;

int temp;

if (head == null) {

return;

} else {

while (current != null) {

// index points to the node next to current

index = current.next;

while (index != null) {

if (current.data > index.data) {

temp = current.data;

current.data = index.data;

index.data = temp;

}

index = index.next;

}

current = current.next;

}

// Print the linked list

public void printList() {

Node tnode = head;

while (tnode != null) {

System.out.print(tnode.data + " ");

tnode = tnode.next;

}

public static void main(String[] args) {

LinkedList llist = new LinkedList();

llist.insertAtEnd(1);

llist.insertAtBeginning(2);

llist.insertAtBeginning(3);

llist.insertAtEnd(4);

llist.insertAfter(llist.head.next, 5);

System.out.println("Linked list: ");

llist.printList();

System.out.println("\nAfter deleting an element: ");

llist.deleteNode(3);

llist.printList();

System.out.println();

int item_to_find = 3;

if (llist.search(llist.head, item_to_find))

System.out.println(item_to_find + " is found");

else

System.out.println(item_to_find + " is not found");

llist.sortLinkedList(llist.head);

System.out.println("\nSorted List: ");

llist.printList();

}

}</code></pre></div>

</div>

<div class="pre-code-wrapper"><div title="Click to copy" class="copy-code-button"></div><pre class="exec" style="max-height: 600px;"><code class="c hljs cpp">// Linked list operations in C

#include <stdio.h>

#include <stdlib.h>

// Create a node

struct Node {

int data;

struct Node* next;

};

// Insert at the beginning

void insertAtBeginning(struct Node** head_ref, int new_data) {

// Allocate memory to a node

struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));

// insert the data

new_node->data = new_data;

new_node->next = (*head_ref);

// Move head to new node

(*head_ref) = new_node;

}

// Insert a node after a node

void insertAfter(struct Node* prev_node, int new_data) {

if (prev_node == NULL) {

printf("the given previous node cannot be NULL");

return;

}

new_node->data = new_data;

new_node->next = prev_node->next;

prev_node->next = new_node;

}

// Insert the the end

void insertAtEnd(struct Node** head_ref, int new_data) {

struct Node* last = *head_ref; /* used in step 5*/

new_node->data = new_data;

new_node->next = NULL;

if (*head_ref == NULL) {

*head_ref = new_node;

return;

}

while (last->next != NULL) last = last->next;

last->next = new_node;

return;

}

// Delete a node

void deleteNode(struct Node** head_ref, int key) {

struct Node *temp = *head_ref, *prev;

if (temp != NULL && temp->data == key) {

*head_ref = temp->next;

free(temp);

return;

}

// Find the key to be deleted

while (temp != NULL && temp->data != key) {

prev = temp;

temp = temp->next;

}

// If the key is not present

if (temp == NULL) return;

// Remove the node

prev->next = temp->next;

free(temp);

}

// Search a node

int searchNode(struct Node** head_ref, int key) {

struct Node* current = *head_ref;

while (current != NULL) {

if (current->data == key) return 1;

current = current->next;

}

return 0;

}

// Sort the linked list

void sortLinkedList(struct Node** head_ref) {

struct Node *current = *head_ref, *index = NULL;

int temp;

if (head_ref == NULL) {

return;

} else {

while (current != NULL) {

// index points to the node next to current

index = current->next;

while (index != NULL) {

if (current->data > index->data) {

temp = current->data;

current->data = index->data;

index->data = temp;

}

index = index->next;

}

current = current->next;

}

// Print the linked list

void printList(struct Node* node) {

while (node != NULL) {

printf(" %d ", node->data);

node = node->next;

}

// Driver program

int main() {

struct Node* head = NULL;

insertAtEnd(&head, 1);

insertAtBeginning(&head, 2);

insertAtBeginning(&head, 3);

insertAtEnd(&head, 4);

insertAfter(head->next, 5);

printf("Linked list: ");

printList(head);

printf("\nAfter deleting an element: ");

deleteNode(&head, 3);

printList(head);

int item_to_find = 3;

if (searchNode(&head, item_to_find)) {

printf("\n%d is found", item_to_find);

} else {

printf("\n%d is not found", item_to_find);

}

sortLinkedList(&head);

printf("\nSorted List: ");

printList(head);

}</code></pre></div>

</div>

<div class="pre-code-wrapper"><div title="Click to copy" class="copy-code-button"></div><pre class="exec" style="max-height: 600px;"><code class="cpp hljs">// Linked list operations in C++

#include <stdlib.h>

#include <iostream>

using namespace std;

// Create a node

struct Node {

int data;

struct Node* next;

};

// Allocate memory to a node

// insert the data

new_node->data = new_data;

new_node->next = (*head_ref);

// Move head to new node

(*head_ref) = new_node;

}

// Insert a node after a node

if (prev_node == NULL) {

cout << "the given previous node cannot be NULL";

return;

}

new_node->data = new_data;

new_node->next = prev_node->next;

prev_node->next = new_node;

}

// Insert at the end

new_node->data = new_data;

new_node->next = NULL;

if (*head_ref == NULL) {

*head_ref = new_node;

return;

}

while (last->next != NULL) last = last->next;

last->next = new_node;

return;

}

// Delete a node

if (temp != NULL && temp->data == key) {

*head_ref = temp->next;

free(temp);

return;

}

// Find the key to be deleted

while (temp != NULL && temp->data != key) {

prev = temp;

temp = temp->next;

}

// If the key is not present

if (temp == NULL) return;

// Remove the node

prev->next = temp->next;

free(temp);

}

// Search a node

bool searchNode(struct Node** head_ref, int key) {

struct Node* current = *head_ref;

while (current != NULL) {

if (current->data == key) return true;

current = current->next;

}

return false;

}

// Sort the linked list

void sortLinkedList(struct Node** head_ref) {

int temp;

if (head_ref == NULL) {

return;

} else {

while (current != NULL) {

// index points to the node next to current

index = current->next;

while (index != NULL) {

if (current->data > index->data) {

temp = current->data;

current->data = index->data;

index->data = temp;

}

index = index->next;

}

current = current->next;

}

// Print the linked list

void printList(struct Node* node) {

while (node != NULL) {

cout << node->data << " ";

node = node->next;

}

// Driver program

int main() {

struct Node* head = NULL;

insertAtEnd(&head, 1);

insertAtBeginning(&head, 2);

insertAtBeginning(&head, 3);

insertAtEnd(&head, 4);

insertAfter(head->next, 5);

cout << "Linked list: ";

printList(head);

cout << "\nAfter deleting an element: ";

deleteNode(&head, 3);

printList(head);

int item_to_find = 3;

if (searchNode(&head, item_to_find)) {

cout << endl << item_to_find << " is found";

} else {

cout << endl << item_to_find << " is not found";

}

sortLinkedList(&head);

cout << "\nSorted List: ";

printList(head);

}</code></pre></div>

</div>

<div class="tutorial-toc"><div class="tutorial-toc__inner"><h3 class="tutorial-toc__title">Table of Contents

<li><a href="#traverse">Traverse a Linked List</a></li>

<li><a href="#add">Insert Elements to a Linked List</a></li>

<li><a href="#delete">Delete from a Linked List</a></li>

<li><a href="#search">Search an Element on a Linked List</a></li>

<li><a href="#sort">Sort Elements of a Linked List</a></li>

<li><a href="#operations">LinkedList Operations in Python, Java, C, and C++</a></li>

</ul></div></div></div> </div>

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