Answer to Question #236729 in C++ for Umer

Question

Write code that performs all operations on doubly Linked List
Note:
1)use class or struct
2)no global declarations

Answer 1

#include <iostream>
using namespace std;




struct Node {
  int d;
  struct Node* nt;
  struct Node* prv;
};




void insertFront(struct Node** h, int d) {
  struct Node* newNode = new Node;


  newNode->d = d;


  newNode->nt = (*h);


  newNode->prv = NULL;


  if ((*h) != NULL)
    (*h)->prv = newNode;


  (*h) = newNode;
}




void insertAfter(struct Node* prev_node, int d) {
  
  if (prev_node == NULL) {
    cout << "Cannot be null";
    return;
  }


  
  struct Node* newNode = new Node;


  
  newNode->d = d;


  newNode->nt = prev_node->nt;


  prev_node->nt = newNode;


  newNode->prv = prev_node;


  if (newNode->nt != NULL)
    newNode->nt->prv = newNode;
}




void insertEnd(struct Node** h, int d) {
  
  struct Node* newNode = new Node;


  
  newNode->d = d;


  newNode->nt = NULL;


  struct Node* temp = *h;


  if (*h == NULL) {
    newNode->prv = NULL;
    *h = newNode;
    return;
  }


  while (temp->nt != NULL)
    temp = temp->nt;




  temp->nt = newNode;


  newNode->prv = temp;
}


void deleteNode(struct Node** h, struct Node* del_node) {
  if (*h == NULL || del_node == NULL)
    return;


  if (*h == del_node)
    *h = del_node->nt;


  if (del_node->nt != NULL)
    del_node->nt->prv = del_node->prv;


  
  if (del_node->prv != NULL)
    del_node->prv->nt = del_node->nt;


  free(del_node);
}
void displayList(struct Node* node) {
  struct Node* last;


  while (node != NULL) {
    cout << node->d << "->";
    last = node;
    node = node->nt;
  }
  if (node == NULL)
    cout << "NULL\n";
}


int main() {
  
  struct Node* h = NULL;


  insertEnd(&h, 1);
  insertFront(&h, 2);
  insertFront(&h, 3);
  insertEnd(&h, 4);


  
  insertAfter(h, 5);


  
  insertAfter(h->nt, 6);


  displayList(h);


  deleteNode(&h, h->nt->nt->nt->nt->nt);


  displayList(h);
}