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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