doubly link list

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

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

struct node* head = NULL, *end= NULL;



void insert(int x){
    struct node* newnode;
    newnode = (struct node*) malloc(sizeof(struct node));
    newnode -> prev = NULL;
    newnode -> data = x;
    newnode -> next = NULL;
    if(head != NULL)
    {
        newnode -> next = head;
        head -> prev = newnode;
    }
    else
    {
        end=newnode;
    }
    head = newnode;

}


void insert_middle(int x, int pos)
{

    struct node* newnode,*cur;
    newnode = (struct node*) malloc(sizeof(struct node));
    newnode -> prev = NULL;
    newnode -> data = x;
    newnode -> next = NULL;
    int index=1;
    cur = head;
    while(cur->next != NULL && index<pos)
    {
        cur=cur->next;
        index++;
    }
    if(cur->next != NULL)
    {
        newnode->next=cur->next;
        newnode->prev=cur;
        (cur->next)->prev = newnode;
        cur->next=newnode;
    }
    else
    {
        newnode->prev = head;
        cur->next = newnode;
    }
}


void l_insert(int x)
{
    struct node* newnode;
    newnode = (struct node*) malloc(sizeof(struct node));
    newnode -> prev = NULL;
    newnode -> data = x;
    newnode -> next = NULL;
    if(head != NULL)
    {
        newnode -> prev = end;
        end -> next = newnode;
    }
    else
    {
        head=newnode;
    }
    end = newnode;

}

void delete_1st()
{
    struct node* cur = head;
    cur = head;
    head=head->next;
    head->prev = NULL;
    free(cur);


}

void Delete_mid()
{
     int pos,i;
    printf("Enter your position for Delete :- ");
    scanf("%d",&pos);
    struct node *cur = head;
    for(i = 1; i < pos ; i++)
    {
        cur = cur -> next;
    }
    if(cur==head){
        head=head->next;
        head->prev = NULL;
        free(cur);
    }
    else if(cur==end){
        end=end->prev;
        end->next = NULL;
        free(cur);
    }
    else{
        (cur->prev)->next = cur->next;
        (cur->next)->prev = cur->prev;
        free(cur);
    }
}


void delete_last()
{
 struct node* temp=end;
    while (temp -> next !=NULL)
    {
        temp = temp -> next;
    }
  end = end->prev;
  end->next=NULL;
    free(temp);
}



void printdata()
{

    struct node* temp = head;
    while(temp != NULL){
        printf("%d >--< ", temp -> data);
        temp = temp -> next;
    }
    printf("\n");

}

int main()
{
    int x, t;

    while(1)
    {   printf("\t\t\t\tPress(1) for First Insert\n\t\t\t\tPress(2) for last Middle\n\t\t\t\tPress(3) for insert Last\n");
        printf("\t\t\t\tPress(4) for delete First\n\t\t\t\tPress(5) for delete Middle\n\t\t\t\tPress(6) for delete last\n");
        printf("\nchoose a option :-");
        scanf("%d",&t);




        if(t==1)
        {
            printf("Input a Data :- ");
            scanf("%d", &x);
            insert(x);
            printdata();
        }

        else if( t == 2)
        {
            int pos;
            printf("Input a Data :- ");
            scanf("%d", &x);
            printf("Enter position for insert middle :- ");
            scanf("%d",&pos);
            insert_middle(x,pos);
            printdata();
        }

        else if(t==3)
        {
            printf("Input a Data :- ");
            scanf("%d", &x);
            l_insert(x);
            printdata();
        }


        else if(t==4)
        {
            delete_1st();
            printdata();
        }

        else if(t==5)
        {
           Delete_mid();
           printdata();
        }

        else if(t==6)
        {
            delete_last();
            printdata();
        }

    }
    return 0;
}