How to create linked list?
Last Updated :
30 May, 2024
In this article, we will explore the process of creating a linked list. A linked list consists of nodes, each containing data and a reference to the next node. We will walk through the steps of defining the node structure, initializing the head of the list, creating new nodes, and linking these nodes to form the list. By the end of this article, you will have a clear understanding of how to implement a linked list.
LinkedList Structure
A LinkedList is a linear data structure where each element is a separate object called a node. Each node contains two fields: one for data and one for the reference to the next node. The first node is called the head. If the LinkedList is empty, the head is a null reference.
How to create linked list?
A linked list is a dynamic data structure that consists of nodes. Each node contains two fields: one for storing data and the other for storing the address of the next node in the list.
Here’s how you can create a linked list:
Step 1: Define the Node Structure
First, we need to define the structure of a node in the linked list. Each node will contain some data and a pointer to the next node.
C++
struct Node {
int data; // The data stored in the node
Node* next; // Pointer to the next node
};
class Node {
int data; // The data stored in the node
Node next; // Pointer to the next node
}
class Node:
def __init__(self, data):
self.data = data # The data stored in the node
self.next = None # Pointer to the next node
class Node {
constructor(data) {
this.data = data; // The data stored in the node
this.next = null; // Pointer to the next node
}
}
Step 2: Initialize the Head of the List
The head of the list is the first node in the list. Initially, the list is empty, so the head is a null pointer.
C++
Step 3: Create New Nodes
To add elements to the list, we create new nodes. Each new node should be dynamically allocated using the new keyword.
C++
Node* newNode = new Node();
Node newNode = new Node();
let newNode = new Node();
After creating a new node, we can set the data field and initialize the next pointer to null.
C++
newNode->data = 1; // Replace 1 with the actual data
newNode->next = nullptr;
newNode.data = 1; // Replace 1 with the actual data
newNode.next = null;
newNode.data = 1 # Replace 1 with the actual data
newNode.next = None
newNode.data = 1; // Replace 1 with the actual data
newNode.next = null;
Step 4: Link the Nodes
If the list is not empty, we need to traverse the list to find the last node and update its next pointer.
C++
if (head == nullptr) {
// The list is empty, so the new node is the head of the list
head = newNode;
} else {
// The list is not empty, traverse the list to find the last node
Node* temp = head;
while (temp->next != nullptr) {
temp = temp->next;
}
// Now temp points to the last node, link the new node
temp->next = newNode;
}
if (head == null) {
// The list is empty, so the new node is the head of the list
head = newNode;
} else {
// The list is not empty, traverse the list to find the last node
Node temp = head;
while (temp.next != null) {
temp = temp.next;
}
// Now temp points to the last node, link the new node
temp.next = newNode;
}
if head is None:
# The list is empty, so the new node is the head of the list
head = newNode
else:
# The list is not empty, traverse the list to find the last node
temp = head
while temp.next is not None:
temp = temp.next
# Now temp points to the last node, link the new node
temp.next = newNode
#this code ios cpntributed by MOnu.
if (head === null) {
// The list is empty, so the new node is the head of the list
head = newNode;
} else {
// The list is not empty, traverse the list to find the last node
let temp = head;
while (temp.next !== null) {
temp = temp.next;
}
// Now temp points to the last node, link the new node
temp.next = newNode;
}
Complete Implemenatation LinkedList:
C++
#include <bits/stdc++.h>
using namespace std;
// Define the Node structure
struct Node {
int data; // The data stored in the node
Node* next; // Pointer to the next node
};
int main()
{
// Initialize the head of the list
Node* head = nullptr;
// Create new nodes and add them to the list
for (int i = 1; i <= 5; i++) {
Node* newNode = new Node();
newNode->data = i; // Replace i with the actual data
newNode->next = nullptr;
// Link the nodes
if (head == nullptr) {
// The list is empty, so the new node is the
// head of the list
head = newNode;
}
else {
// The list is not empty, traverse the list to
// find the last node
Node* temp = head;
while (temp->next != nullptr) {
temp = temp->next;
}
// Now temp points to the last node, link the
// new node
temp->next = newNode;
}
}
// Print the list
Node* temp = head;
while (temp != nullptr) {
cout << temp->data << " ";
temp = temp->next;
}
cout << endl;
// Free up the memory
while (head != nullptr) {
Node* temp = head;
head = head->next;
delete temp;
}
return 0;
}
// Import necessary libraries
import java.util.*;
// Define the Node class
class Node {
int data; // The data stored in the node
Node next; // Reference to the next node
// Node constructor
public Node(int data) {
this.data = data;
this.next = null;
}
}
public class Main {
public static void main(String[] args) {
// Initialize the head of the list
Node head = null;
// Create new nodes and add them to the list
for (int i = 1; i <= 5; i++) {
Node newNode = new Node(i); // Replace i with the actual data
// Link the nodes
if (head == null) {
// The list is empty, so the new node is the
// head of the list
head = newNode;
} else {
// The list is not empty, traverse the list to
// find the last node
Node temp = head;
while (temp.next != null) {
temp = temp.next;
}
// Now temp points to the last node, link the
// new node
temp.next = newNode;
}
}
// Print the list
Node temp = head;
while (temp != null) {
System.out.print(temp.data + " ");
temp = temp.next;
}
System.out.println();
// No explicit memory deallocation is needed in Java
// The Java Garbage Collector will automatically free up the memory
}
}
# Define the Node class
class Node:
def __init__(self, data=None):
self.data = data # The data stored in the node
self.next = None # Pointer to the next node
# Initialize the head of the list
head = None
# Create new nodes and add them to the list
for i in range(1, 6):
new_node = Node(i) # Replace i with the actual data
# Link the nodes
if head is None:
# The list is empty, so the new node is the
# head of the list
head = new_node
else:
# The list is not empty, traverse the list to
# find the last node
temp = head
while temp.next is not None:
temp = temp.next
# Now temp points to the last node, link the
# new node
temp.next = new_node
# Print the list
temp = head
while temp is not None:
print(temp.data, end=" ")
temp = temp.next
print()
// Define the Node class
class Node {
constructor(data) {
this.data = data; // The data stored in the node
this.next = null; // Pointer to the next node
}
}
// Main function
function main() {
// Initialize the head of the list
let head = null;
// Create new nodes and add them to the list
for (let i = 1; i <= 5; i++) {
let newNode = new Node(i); // Replace i with the actual data
// Link the nodes
if (head === null) {
// The list is empty, so the new node is the head of the list
head = newNode;
} else {
// The list is not empty, traverse the list to find the last node
let temp = head;
while (temp.next !== null) {
temp = temp.next;
}
// Now temp points to the last node, link the new node
temp.next = newNode;
}
}
// Print the list
let temp = head;
let listStr = "";
while (temp !== null) {
listStr += temp.data + " ";
temp = temp.next;
}
console.log(listStr.trim());
// Free up the memory
while (head !== null) {
let temp = head;
head = head.next;
temp = null;
}
}
// Call the main function
main();
Conclusion
Creating a LinkedList involves several steps: defining the Node structure, initializing the LinkedList, and implementing methods to add and traverse nodes. While the implementation can vary depending on the programming language, the fundamental concepts remain the same. Understanding these steps is crucial for anyone learning data structures and algorithms.
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