Doubly linked list

Doubly linked list.

In doubly linked list each node is divided into three parts.
1.LINK:- It holds address of previous node of linked list.
2.INFO:-It holds value of node.
3.RLINK:-It holds address of next node

In doubly linked list LINK part of first node and RLINK of last node always contain NULL.
   

Advantage:
It is use to avoid the drawback of singly linked list.we know that in singly linked list we can traversed node left to right/foreword direction but doubly linked list supports bidirectional traversing/both backward and foreword direction

Disadvantage:
It uses more memory space rather than singly linked list because it consist left and right pointer.

(If you not read previous topic singly linked list click on link)↧ 

       singly linked list program choice based

Doubly linked list  program choice base

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<process.h>
struct node
{
    int info;
    struct node *llink,  * rlink;
};
void create();
void display();
void sinsert();
void pinsert();
void einsert();
void sdel();
void pdel();
void edel();
struct node *first=NULL,*last=NULL,*new1;
int main()
{
    int choice;
    do
    {
         system("cls");

        printf("Press 1 for create node.\npress 2 for display list.\npress 3 for enter node at first position\npress 4 for insert at perticular position\npress 5 to insert at last position\npress 6 to delete first node\npress 7 to delete perticular position\npress 8 to delete last node\npress 9 for exit .........-->\t");

        scanf("%d",&choice);

        switch( choice)
        {
        case 1:
            create(); break;
        case 2:
            display();break;
        case 3:
            sinsert(); break;
        case 4:
            pinsert(); break;
        case 5:
            einsert(); break;
        case 6:
            sdel(); break;
        case 7:
            pdel();break;
        case 8:
            edel(); break;
        case 9:
            exit(0);
        default:
            printf("invalid ! choice");
        }

    }
    while(choice>=1 &&choice<=8);
    return 0;

}
// create a new node
 void create(){
     new1=(struct node*)malloc (sizeof(struct node));
     printf("enter the value of node=");
     scanf("%d",&new1->info);
     new1->rlink=NULL;
     new1->llink=NULL;
     if(first== NULL)
        {
            first=new1;
         last=new1;
        }
     else
     {
         last->rlink=new1;
         new1->llink=last;
          last=new1;

     }


}
//display in doubly linked list
void display()
{
    struct node *temp;
if(first== NULL)
    printf("there is no any node !");
else{
        printf("all nodes are=\n");
        for(temp=first;temp!=NULL;temp=temp->rlink)
        {
            printf("\t%d\n",temp->info);
        }


}
system("pause");
}
//insert at first position in doubly linked list
void sinsert()
{
    new1=(struct node*)malloc (sizeof(struct node));
    printf("enter value of new node=");
    scanf("%d",&new1->info);
    new1->llink=NULL;
    new1->rlink=first;
    first->llink=new1;
    first=new1;



}
//insert at particular position in doubly linked list
void pinsert()
{
 new1=(struct node*)malloc(sizeof(struct node));
struct node *temp;
int position,loop=1,count1=0;
printf("enter position where you want to insert");
scanf("%d",&position);

  for(temp=first;temp!=NULL;temp=temp->rlink)
        {
           count1++;
        }
if(position>=count1||position<0)
    printf("position not exist!");
else{
printf("enter value of node");
scanf("%d",&new1->info);
temp=first;
if(position==1)
{
   new1->llink=NULL;
    new1->rlink=first;
    first->llink=new1;
    first=new1;
}
else{
while(loop<position-1)
{
    temp=temp->rlink;
    loop++;
}
    new1->llink=temp;
new1->rlink=temp->rlink;
temp->rlink=new1;




}
}
system("pause");
}
//insert at last position in doubly linked list
void einsert()
{
    new1=(struct node*)malloc(sizeof(struct node));
    printf("enter the the value");
    scanf("%d",&new1->info);
    new1->rlink=NULL;
    last->rlink=new1;
    last=new1;

}
//delete at first position in doubly linked list
void sdel()
{
    printf("record deleted from first is=%d\n",first->info);
 first=first->rlink;
system("pause");
}
//delete at particular position in doubly linked list
void pdel()
{

    struct node *temp,*pre;
int position,loop=1,count1=0;
printf("enter position which you want to delete");
scanf("%d",&position);

  for(temp=first;temp!=NULL;temp=temp->rlink)
        {
           count1++;
        }
if(position>=count1||position<0)
    printf("position not exist!");
else{

temp=first;
if(position==1)
{
   first=first->rlink;
}
else{
while(loop<position)
{
    pre=temp;
    temp=temp->rlink;
    loop++;
}
    pre->rlink=temp->rlink;
    temp=temp->rlink;
    temp->llink=pre;




}
}
system("pause");


}
//delete at last position in doubly linked list
void edel()
{
    if(first==NULL)
        printf("no any node avialable");
    else{
    printf("deleted record=%d\n",last->info);
    last=last->llink;
    last->rlink=NULL;
    }
    system("pause");
}