﻿ C++ - Count number of nodes in a doubly linked list

# C++ Linked List Exercises: Count number of nodes in a doubly linked list

## C++ Linked List: Exercise-17 with Solution

Write a program in C++ to create a doubly linked list of n nodes and count the number of nodes.

Test Data:
Doubly linked list is as follows:
Traversal in Forward direction:
Orange White Green Red
Traversal in Reverse direction:
Red Green White Orange
Total number of nodes = 4

Sample Solution:

C++ Code:

`````` #include <iostream> // Including input-output stream header file

using namespace std; // Using standard namespace

// A doubly linked list node
struct Node {
string data; // Data field to store string data
struct Node* next; // Pointer to the next node
struct Node* prev; // Pointer to the previous node
};

// Function to append data at the front of the doubly linked list
{
// Create a new node and allocate memory.
struct Node* newNode = new Node;

// Assign data to the new node
newNode->data = new_data;

// A new node has been added with the name head and the previous node
// set to null, since it is being added at the front.
newNode->prev = NULL;

// Previous head is the new node

// Head points to new node
}

// Function to count the number of nodes in the doubly linked list
{
int ctr = 0; // Counter to count the nodes
while (head != NULL) { // Loop through the linked list until the end is reached
ctr++; // Increment the counter for each node encountered
}
return ctr; // Return the total count of nodes
}

// Function to display contents of the doubly linked list
{
Node* last_node;
cout << "\n\nTraversal in Forward direction:\n";
cout << " " << head->data << " "; // Displaying data in forward direction
}
cout << "\nTraversal in Reverse direction:\n";
while (last_node != NULL) {
cout << " " << last_node->data << " "; // Displaying data in reverse direction
last_node = last_node->prev;
}
}

// Main program
int main() {
append_data(&head, "Red"); // Appending "Red" at the front of the list
append_data(&head, "Green"); // Appending "Green" at the front of the list
append_data(&head, "White"); // Appending "White" at the front of the list
append_data(&head, "Orange"); // Appending "Orange" at the front of the list
cout<<"Doubly linked list is as follows: ";
int totalNode = NodeCount(head); // Calculating the total number of nodes in the list
cout << "\n\nTotal number of nodes = " << totalNode; // Displaying the total number of nodes
return 0; // Returning from the main function
}
``````

Sample Output:

```Doubly linked list is as follows:

Traversal in Forward direction:
Orange  White  Green  Red
Traversal in Reverse direction:
Red  Green  White  Orange

Total number of nodes = 4
```

Flowchart:

CPP Code Editor: