# C++ - Circular Singly Linked List

A circular singly linked list is a linear data structure, in which the elements are stored in the form of a node. Each node contains two sub-elements. A data part that stores the value of the element and the next part that stores the pointer to the next node as shown in the below image:

The first node also known as HEAD is always used as a reference to traverse the list. The last node points to HEAD. A circular singly linked list can be visualized as a chain of nodes, where every node points to the next node. Along with this, next of the last node is linked to the head node.

## Implementation of Circular Singly Linked List

### Representation:

In C++, doubly linked list can be created using a class and a Node using structures. The LinkedList class contains Node as class member.

//node structure struct Node { int data; Node* next; }; class LinkedList { public: Node* head; public: //constructor to create an empty LinkedList LinkedList(){ head = NULL; } };

### Create a Circular Singly Linked List

Let us create a simple circular singly linked list which contains three data nodes.

#include <iostream> using namespace std; //node structure struct Node { int data; Node* next; }; class LinkedList { public: Node* head; public: //constructor to create an empty LinkedList LinkedList(){ head = NULL; } }; // test the code int main() { //create an empty LinkedList LinkedList MyList; //Add first node. Node* first = new Node(); first->data = 10; //linking with head node MyList.head = first; //linking next of the node with head first->next = MyList.head; //Add second node. Node* second = new Node(); second->data = 20; //linking with first node first->next = second; //linking next of the node with head second->next = MyList.head; //Add third node. Node* third = new Node(); third->data = 30; //linking with second node second->next = third; //linking next of the node with head third->next = MyList.head; return 0; }

### Traverse a Circular Singly Linked List

A circular singly linked list can be traversed from any node of the list using a temp node. Keep on moving the temp node to the next one and displaying its content. Stop the traversal, after reaching the starting node.

#include <iostream> using namespace std; //node structure struct Node { int data; Node* next; }; class LinkedList { public: Node* head; public: //constructor to create an empty LinkedList LinkedList(){ head = NULL; } //display the content of the list void PrintList() { Node* temp = head; if(temp != NULL) { cout<<"The list contains: "; while(true) { cout<<temp->data<<" "; temp = temp->next; if(temp == head) break; } cout<<endl; } else { cout<<"The list is empty.\n"; } } }; // test the code int main() { //create an empty LinkedList LinkedList MyList; //Add first node. Node* first = new Node(); first->data = 10; //linking with head node MyList.head = first; //linking next of the node with head first->next = MyList.head; //Add second node. Node* second = new Node(); second->data = 20; //linking with first node first->next = second; //linking next of the node with head second->next = MyList.head; //Add third node. Node* third = new Node(); third->data = 30; //linking with second node second->next = third; //linking next of the node with head third->next = MyList.head; //print the content of list MyList.PrintList(); return 0; }

The above code will give the following output:

The list contains: 10 20 30