Deletion in Double Linked list

 

#include <stdio.h>

#include <stdlib.h>

struct node

{

    int data;

    struct node *prev;

    struct node *link;

};

void display(struct node *ptr)

{

    while (ptr != NULL)

    {

        printf(" %d ", ptr->data);

        ptr = ptr->link;

    }

}

struct node *del_beg(struct node *head)

{

    struct node *ptr = head;

    head = head->link;

    head->prev = NULL;

    free(ptr);

    return head;

}

struct node *del_end(struct node *head)

{

    struct node *ptr = head;

    while (ptr->link != NULL)

    {

        ptr = ptr->link;

    }

    ptr->prev->link = NULL;

    free(ptr);

    return head;

}

struct node *del_pos(struct node *head, int pos)

{

    struct node *ptr = head;

    struct node *i;

    int j = 0;

    while (j != pos - 1)

    {

        ptr = ptr->link;

        j++;

    }

    i = ptr->link;

    ptr->link = i->link;

    i->link->prev = ptr;

    free(i);

    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->prev = NULL;

    a->data = 1;

    a->link = b;

    b->prev = a;

    b->data = 2;

    b->link = c;

    c->prev = b;

    c->data = 3;

    c->link = d;

    d->prev = c;

    d->data = 4;

    d->link = NULL;

    display(a);

    printf("\n");

    // a = del_beg(a);

    // a = del_end(a);

    a = del_pos(a, 2);

    display(a);

    return 0;

}