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>
using namespace std;
// A doubly linked list node
struct Node {
string data;
struct Node* next;
struct Node* prev;
};
//Append node at the front of the list
void append_data(Node** head, string new_data)
{
//Create a new node and allocate memory.
struct Node* newNode = new Node;
//assign data to 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->next = (*head);
newNode->prev = NULL;
//previous head is new node
if ((*head) != NULL)
(*head)->prev = newNode;
//head points to new node
(*head) = newNode;
}
int NodeCount(struct Node* head)
{
int ctr = 0;
while (head != NULL) {
ctr++;
head = head->next;
}
return ctr;
}
// Following function display contents of the doubly linked list
void displayDlList(Node* head)
{
Node* last_node;
cout << "\n\nTraversal in Forward direction:\n";
while (head != NULL) {
cout << " " << head->data << " ";
last_node = head;
head = head->next;
}
cout << "\nTraversal in Reverse direction:\n";
while (last_node != NULL) {
cout << " " << last_node->data << " ";
last_node = last_node->prev;
}
}
//main program
int main() {
/* Start with the empty list */
struct Node* head = NULL;
append_data(&head, "Red");
append_data(&head, "Green");
append_data(&head, "White");
append_data(&head, "Orange");
cout<<"Doubly linked list is as follows: ";
displayDlList(head);
int totalNode = NodeCount(head);
cout << "\n\nTotal number of nodes = " << totalNode;
return 0;
}
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:
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Previous C++ Exercise: Reverse doubly linked list.
Next C++ Exercise: Insert a node at the beginning of a Doubly Linked List.
What is the difficulty level of this exercise?
C++ Programming: Tips of the Day
C++: const reference, before vs after type-specifier
No difference as const is read right-to-left with respect to the &, so both represent a reference to an immutable Fred instance.
Fred&const would mean the reference itself is immutable, which is redundant; when dealing with const pointers both Fred const* and Fred* const are valid but different.
It's a matter of style, but using const as a suffix since it can be applied consistently including const member functions.
Ref: https://bit.ly/3NmkTS7
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