Insertion in Circular Linked list

 

#include <stdio.h>

#include <stdlib.h>

struct node

{

    int data;

    struct node *link;

};

void display(struct node *head)

{

    struct node *ptr = head;

    do

    {

        printf(" %d ", ptr->data);

        ptr = ptr->link;

    } while (ptr != head);

}

struct node *insert_beg(struct node *head,int s){

    struct node *e = malloc(sizeof(struct node));

    e->data = s;

    struct node *ptr;

    ptr = head->link;

    while(ptr->link!=head){

        ptr=ptr->link;

    }

    ptr->link = e;

    e->link = head;

    head = e;

    return head;

}

struct node *insert_end(struct node *head,int s){

    struct node *e = malloc(sizeof(struct node));

    e->data = s;

    struct node *ptr;

    ptr = head->link;

    while(ptr->link!=head){

        ptr=ptr->link;

    }

    ptr->link = e;

    e->link = head;

    return head;

}

struct node *insert_pos(struct node *head,int s,int pos){

    struct node *e = malloc(sizeof(struct node));

    struct node *ptr=head;

    int j=0;

    while(j!=pos-1){

        ptr=ptr->link;

        j++;

    }

    e->data = s;

    e->link = ptr->link;

    ptr->link = e;

    return head;

}  

int main()

   

{

    struct node *a;

    struct node *b;

    struct node *c;

    struct node *d;

    a = malloc(sizeof(struct node));

    b = malloc(sizeof(struct node));

    c = malloc(sizeof(struct node));

    d = malloc(sizeof(struct node));

    a->data = 1;

    a->link = b;

    b->data = 2;

    b->link = c;

    c->data = 3;

    c->link = d;

    d->data = 4;

    d->link = a;

    display(a);

    printf("\n");

    // a = insert_beg(a,0);

    // a = insert_end(a,5);

    a = insert_pos(a,0,2);

    display(a);

    return 0;

}