Description
To add node in the beginning of the list - case 1: When list is empty create a node and assign the address of newly created node to the head Case 2: When list has few elements step 1 : create a new node step 2 : Assign address of head to the next field of newly created node step 3 : Assign the address of newly created node to head Note: Here head contains the address of first node
C/C++
/* C program of Program To Add a node in the beginning of singly linked list */
//Save it as add_node_beginning_singly_linked_list.c
#include<stdio.h>
#include<malloc.h>
struct node *create(int);
void display(struct node *);
struct node *insert_beg(struct node *);
//Declaring node
struct node
{
int data;
struct node *next;
};
int main()
{
int n;
struct node *head;
printf("Enter number of nodes : ");
scanf("%d",&n);
//Calling function to create node
head=create(n);
//Calling function to display list
printf("\nThe linked list is - \n");
display(head);
//Function to insert the node at beginning of linked list
head=insert_beg(head);
//Calling function to display list after addition of node at beginning
printf("\nThe linked list after addition of node at beginning-\n");
display(head);
return 0;
}
struct node *create(int n)
{
int i;
struct node *head=NULL;
struct node *ptr,*newNode;
for(i=0;i<n;i++)
{
//Creating a node
newNode=(struct node*)malloc(sizeof(struct node));
//Assigning data to newly created node
printf("Enter the value of %d node : ",i+1);
scanf("%d",&newNode->data);
newNode->next=NULL;
/*If list is empty assign the address of newly created node
to head*/
if(head==NULL)
{
head=newNode;
}
else
{
/* If list already have few elements then loop through
list and add newly created node at the end of list*/
ptr=head;
while(ptr->next!=NULL)
{
ptr=ptr->next;
}
ptr->next=newNode;
}
}
return head;
}
void display(struct node *head)
{
struct node *ptr;
//If list is empty
if(head==NULL)
{
printf("The linked list is empty");
}
else
{
/*If list has elements then loop through the loop and
print elements one by one in sequential manner*/
ptr=head;
while(ptr!=NULL)
{
printf("The node value = %d and their address = %u\n",ptr->data,ptr);
ptr=ptr->next;
}
}
}
//Function to insert a node in the beginning
struct node *insert_beg(struct node *head){
int data;
struct node *ptr, *newNode;
//Creating new node to be added
newNode=(struct node*)malloc(sizeof(struct node));
printf("\nEnter the node data of new node : ");
scanf("%d",&newNode->data);
newNode->next=NULL;
//assign the address of newly created node to the head if list is empty
if(head==NULL){
head=newNode;
}else{
/*Assign the address of head to next field of newly created node*/
newNode->next=head;
/*Assign the address of newly created node to the head*/
head=newNode;
}
return head;
}
Input: Enter number of nodes : 5 Enter the value of 1 node : 4 Enter the value of 2 node : 1 Enter the value of 3 node : 9 Enter the value of 4 node : 6 Enter the value of 5 node : 3 The linked list is - The node value = 4 and their address = 7015768 The node value = 1 and their address = 7015800 The node value = 9 and their address = 7015816 The node value = 6 and their address = 7015832 The node value = 3 and their address = 7015848 Enter the node data of new node : 7 Output: The linked list after addition of node at beginning- The node value = 7 and their address = 7015864 The node value = 4 and their address = 7015768 The node value = 1 and their address = 7015800 The node value = 9 and their address = 7015816 The node value = 6 and their address = 7015832 The node value = 3 and their address = 7015848
Java
/* Java program of Program To Add a node in the beginning of singly linked list */
//Save it as AddNodeBeginningSinglyLinkedList.java
import java.io.*;
import java.util.Scanner;
public class AddNodeBeginningSinglyLinkedList {
//Declaring node
class Node{
int data;
Node next;
public Node(int data) {
this.data=data;
//Assigning null value to the next field
this.next=null;
}
}
public Node head=null;
//Function to add node
public void addNode(int data) {
//Creating a new node
Node newNode = new Node(data);
/*If list is empty assign the address of newly created node
to head*/
if(head==null) {
head=newNode;
}else {
/* If list already have few elements then loop through
list and add newly created node at the end of list*/
Node ptr=head;
while(ptr.next!=null) {
ptr=ptr.next;
}
ptr.next=newNode;
}
}
public void display() {
Node ptr=head;
//If list is empty
if(ptr==null) {
System.out.println("The list is empty");
return;
}
System.out.println("The nodes of lists are : ");
/*If list has elements then loop through the loop and
print elements one by one in sequential manner*/
while(ptr!=null) {
System.out.print(ptr.data+" ");
ptr=ptr.next;
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
AddNodeBeginningSinglyLinkedList list = new AddNodeBeginningSinglyLinkedList();
System.out.println("Enter number of node you want to enter : ");
int n = scanner.nextInt();
for(int i=0;i<n;i++) {
System.out.println("Enter value of "+(i+1)+" node : ");
int val = scanner.nextInt();
list.addNode(val);
}
//Calling function to display list
list.display();
System.out.println("\nEnter the value you want to enter at beginning : ");
int beg = scanner.nextInt();
list.insert_beg(beg);
//Calling function to display list after addition of node in the beginning
System.out.println("After addition of node in the beginning - ");
list.display();
}
//Function to add node in the beginning
private void insert_beg(int beg) {
//Creating new node to be added
Node nodeToAdd = new Node(beg);
//assign the address of newly created node to the head if list is empty
if(head==null) {
head=nodeToAdd;
}else {
/*Assign the address of head to next field of newly created node*/
nodeToAdd.next=head;
/*Assign the address of newly created node to the head*/
head=nodeToAdd;
}
}
}
Input: Enter number of node you want to enter : 3 Enter value of 1 node : 4 Enter value of 2 node : 1 Enter value of 3 node : 9 The nodes of lists are : 4 1 9 Enter the value you want to enter at beginning : 8 Output: After addition of node in the beginning - The nodes of lists are : 8 4 1 9
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