Insert Node At The Beginning of The Circular Linked List

Insert Node At The Beginning of The Circular Linked List

In this post, you will learn how you can insert a node at the beginning of the circular linked list.

Code

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

struct node *head = NULL;

void insertAtBeginning(int a){
    struct node *new = malloc(sizeof(struct node));
    new->data = a;

    if(head==NULL){
        new->next=new;
        head = new;
    }
    else{
        struct node *temp = head;
        while (temp->next!=NULL)
        {
            temp = temp->next;
        }
        temp->next = new;
        new->next = head;
        head = new;
        
    }
}

In this code we are doing following things:

1. If linked list is empty then make the node as head and its next pointer points to itself.
2. Else make a new pointer say temp which iterates from first to last node.
3. Then insert the node at the end of the linked list and make the last node as head which points to previous head.
4. So this is how we insert a new node at the beginnig of the circular linked list.

So this is how the function is working.

#include<stdio.h>
#include<stdlib.h>

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

struct node *head = NULL;

void insertAtBeginning(int a)
{
    struct node *new = (struct node *)malloc(sizeof(struct node));
    new->data = a;
    new->next = head;

    struct node *temp = head;
    if (head != NULL)
    {
        while (temp->next != head)
            temp = temp->next;
            temp->next = new;
    }
    else{
        new->next = new; 
        head = new;
    }
}


void print()
{
    struct node *temp = head;
    if (head != NULL)
    {
        do
        {
            printf("%d ", temp->data);
            temp = temp->next;
        }
        while (temp != head);
    }
}


int main()
{
    insertAtBeginning(1);
    insertAtBeginning(2);
    insertAtBeginning(3);
    print();

    return 0;
}