write a program to create a doubly link list.
1->creation.
2->insertion
3->deletion.

#include<stdio.h>
#include<stdlib.h>
void creation(void);
void display(void);
void create_node(void);
void insert_end(void);
void insert_beginning(void);
void insert_middle(void);
void deletion(void);
struct link_list
{
    int data;
    struct link_list *next;
    struct link_list *prev;
}*start=NULL;
typedef struct link_list node;
node *current,*nnew;

int main()
{
    int a;
    char ch;
    creation();
    do
    {
        printf("\n enter your choice\n1->display\n2->insert at end\n3->insert at beginning\n4->insert b/w two nodes\n5->deletion\n");
        scanf("%d",&a);
        switch(a)
        {
            case 1:
            display();
            break;
            case 2:
            insert_end();
            break;
            case 3:
            insert_beginning();
            break;
            case 4:
            insert_middle();
            break;
            case 5:
            deletion();
            break;
            default:
            printf("wrong choice");
        }
        printf("\n press any key to continue and press n to quit");
        scanf("%s",&ch);
    }while(ch!='n');
    return (0);
}

void creation(void)
{
    int i=0,k;
    printf("how many nodes you want to create");
    scanf("%d",&i);
    while(i!=0)
    {
        nnew=malloc(sizeof(node));
        nnew->next=NULL;
        nnew->prev=NULL;
        if(start==NULL)
        {
            printf("enter any integer data");
            scanf("%d",&k);
            nnew->data=k;
            start=nnew;
            current=start;
        }
        else
        {
            printf("enter any integer data");
            scanf("%d",&k);
            nnew->data=k;
            current->next=nnew;
            nnew->prev=current;
            current=nnew;
        }
        i--;
    }
}

void create_node(void)
{
    int k;
    nnew=malloc(sizeof(node));
    nnew->next=NULL;
    nnew->prev=NULL;
    printf("enter the data for this node");
    scanf("%d",&k);
    nnew->data=k;
}

void display(void)
{
    int l;
    printf("enter 1 to display list from beginning and 2 to display it from last");
    scanf("%d",&l);
    current=start;
    if(l==1)
    {
        int i=1;
        while(current!=NULL)
        {
            printf("%d:: %d\n",i ,current->data);
            current=current->next;
            i++;
        }
    }
    if(l==2)
    {
        int i=1;
        current=start;
        while(current->next!=NULL)
        {
            current=current->next;
            i++;
        }
        do
        {
            printf("%d:: %d\n",i ,current->data);
            current=current->prev;
            i--;
        }while(current!=NULL);
    }
}

void insert_end(void)
{
    create_node();
    current=start;
    while(current->next!=NULL)
    {
        current=current->next;
    }
    if(current->next==NULL)
    {
        current->next=nnew;
        nnew->prev=current;
        current=nnew;
        printf("node inserted successfully");
    }
}
void insert_beginning(void)
{
    create_node();
    nnew->next=start;
    start=nnew;
    printf("node inserted successfully\n");
}

void insert_middle(void)
{
    int a,i,pos;
    current=start;
    printf("enter the serial number of node accept first and the last node ");
    scanf("%d",&pos);
    printf("enter 1 to insert after the selected node and 2 for before ");
    scanf("%d",&a);
    if(a==1)
    {
        current=start;
        for(i=1;i<pos;i++)
        {
            current=current->next;
        }
        nnew->next=current->next;
        nnew->prev=current;
        current->next=nnew;
    }
    else if(a==2)
    {
        current=start;
        for(i=1;i<pos-1;i++)
        {
            current=current->next;
        }
        nnew->next=current->next;
        nnew->prev=current;
        current->next=nnew;
    }
    else
    {
        printf("wrong choice");
    }
}
void deletion(void)
{
    int y,i;
    current=start;
    printf("enter the serial number of node you want to delete ");
    scanf("%d",&y);
    if(y==1)
    {
        start=start->next;
    }
    else
    {
        for(i=1;i<y-1;i++)
        {
            current=current->next;
        }
        if(current->next->next==NULL)
        {
            current->next=NULL;
        }
        else
        {
            current->next=current->next->next;
        }
    }
    printf("node is deleted");
}