Delete a node in a Doubly Linked List in C++

C++Server Side ProgrammingProgramming

In this tutorial, we are going to learn how to delete a node in doubly linked list.

Let's see the steps to solve the problem.

  • Write struct with data, prev and next pointers.

  • Write a function to insert the node into the doubly linked list.

  • Initialize the doubly linked list with dummy data.

  • Take a node to delete.

  • Write a function to delete the node. Consider the following three cases while deleting the node.

    • If the node is head node, then move the head to next node.

    • If the node is middle node, then link the next node to the previous node

    • If the node is end node, then remove the previous node link. Let's see the code.

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
struct Node {
   int data;
   Node *prev, *next;
};
void deleteNode(Node** head_ref, Node* del) {
   if (*head_ref == NULL || del == NULL) {
      return;
   }
   if (*head_ref == del) {
      *head_ref = del->next;
   }
   if (del->next != NULL) {
      del->next->prev = del->prev;
   }
   if (del->prev != NULL) {
      del->prev->next = del->next;
   }
   free(del);
   return;
}
void insertNode(Node** head_ref, int new_data) {
   Node* new_node = new Node();
   new_node->data = new_data;
   new_node->prev = NULL;
   new_node->next = (*head_ref);
   if ((*head_ref) != NULL) {
      (*head_ref)->prev = new_node;
   }
   (*head_ref) = new_node;
}
void printLinkedList(Node* node) {
   while (node != NULL) {
      cout << node->data << " -> ";
      node = node->next;
   }
}
int main() {
   Node* head = NULL;
   insertNode(&head, 1);
   insertNode(&head, 2);
   insertNode(&head, 3);
   insertNode(&head, 4);
   insertNode(&head, 5);
   cout << "Linked List before deletion:" << endl;
   printLinkedList(head);
   deleteNode(&head, head->next);
   cout << "\nLinked List after deletion:" << endl;
   printLinkedList(head);
   return 0;
}

Output

If you execute the above program, then you will get the following result.

Linked List before deletion:
5 -> 4 -> 3 -> 2 -> 1 ->
Linked List after deletion:
5 -> 3 -> 2 -> 1 ->

Conclusion

If you have any queries in the tutorial, mention them in the comment section.

raja
Published on 30-Dec-2020 11:14:38
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