Write a program in c to insert a node at the end of a circular linked list.

C Exercises: Insert a node at the end of a circular linked list

C Exercises: Insert a node at the beginning of a circular linked list

Q. Program to insert a new node at the end of the circular linked list.

Explanation

In this program, we will create a circular linked list and insert every new node at the end of the list. If the list is empty, then head and tail will point to the newly added node. If the list is not empty, the newly added node will become the new tail of the list. The previous tail will point to new node as its next node. Since it is a circular linked list; the new tail will point to head. In other words, the new node will become last node (tail) of the list, and the previous tail will be the second last node.

After inserting new node to the end of the list

New represents the newly added node. D is the previous tail. When new is added to the end of the list, it will become new tail and D will point to new.

Algorithm

1. Define a Node class which represents a node in the list. It has two properties data and next which will point to the next node.
2. Define another class for creating the circular linked list and it has two nodes: head and tail. It has two methods: addAtEnd() and display() .
3. addAtEnd() will add the node to the end of the list:
   1. It first checks whether the head is null (empty list), then it will insert the node as the head.
   2. Both head and tail will point to the newly added node.
   3. If the list is not empty, then the newly added node will become the new tail, and previous tail will point to new node as its next node. The new tail will point to the head.
4. display() will show all the nodes present in the list.
   1. Define a new node 'current' that will point to the head.
   2. Print current.data till current will points to head again.
   3. Current will point to the next node in the list in each iteration.

C Program for Insertion at the end in circular linked list

July 20, 2020

Linked List | Set 2 (Inserting a node)

We have introduced Linked Lists in the previous post. We also created a simple linked list with 3 nodes and discussed linked list traversal.
All programs discussed in this post consider the following representations of linked list.

C++

// A linked list node class Node { public: int data; Node *next; }; // This code is contributed by rathbhupendra

C

// A linked list node struct Node { int data; struct Node *next; };

Java

// Linked List Class class LinkedList { Node head; // head of list /* Node Class */ class Node { int data; Node next; // Constructor to create a new node Node(int d) {data = d; next = null; } } }

Python

# Node class class Node: # Function to initialize the node object def __init__(self, data): self.data = data # Assign data self.next = None # Initialize next as null # Linked List class class LinkedList: # Function to initialize the Linked List object def __init__(self): self.head = None

C#

/* Linked list Node*/ public class Node { public int data; public Node next; public Node(int d) {data = d; next = null; } }

Javascript

<script> // Linked List Class var head; // head of list /* Node Class */ class Node { // Constructor to create a new node constructor(d) { this.data = d; this.next = null; } } // This code is contributed by todaysgaurav </script>

In this post, methods to insert a new node in linked list are discussed. A node can be added in three ways
1) At the front of the linked list
2) After a given node.
3) At the end of the linked list.

Program for all operations on circular linked list in C

In a Circular linked list, every element has a link to its next element in the sequence and the last element has a link to the first element. A circular linked list is similar to the singly linked list except that the last node points to the first node. Below is the image to illustrate the same:

Some common operations of a circular linked list are implemented below:

Insertion at the beginning: Inserting a new node as the first node. The next pointer of last will point to this node and this new node will point to the previous first node.

C

// C program for the above operation #include <stdio.h> #include <stdlib.h> // Structure of a linked list node struct node { int info; struct node* next; }; // Pointer to last node in the list struct node* last = NULL; // Function to insert a node in the // starting of the list void insertAtFront() { // Stores the number to be inserted int data; // Initialize a new node struct node* temp; temp = (struct node*)malloc(sizeof(struct node)); // Input data printf("\nEnter data to be " "inserted: \n"); scanf("%d", &data); // If the new node is the only // node in the list if (last == NULL) { temp->info = data; temp->next = temp; last = temp; } // Else last node contains the // reference of the new node and // new node contains the reference // of the previous first node else { temp->info = data; temp->next = last->next; // last node now has reference // of the new node temp last->next = temp; } } // Function to print the list void viewList() { // If list is empty if (last == NULL) printf("\nList is empty\n"); // Else print the list else { struct node* temp; temp = last->next; // While first node is not // reached again, print, // since the list is circular do { printf("\nData = %d", temp->info); temp = temp->next; } while (temp != last->next); } } // Driver Code int main() { // Function Call insertAtFront(); insertAtFront(); insertAtFront(); // Print list viewList(); return 0; }

Output:

Insertion at the end: Inserting a new node as the last node. The next pointer of last will point to this node and this new node will point to the first node.

C

// C program for the above operation #include <stdio.h> #include <stdlib.h> // Structure of a linked list node struct node { int info; struct node* next; }; // Pointer to last node in the list struct node* last = NULL; // Function to add a new node at the // end of the list void addatlast() { // Stores number to be inserted int data; // Initialize a new node struct node* temp; temp = (struct node*)malloc(sizeof(struct node)); // Input data printf("\nEnter data to be " "inserted : \n"); scanf("%d", &data); // If the new node is the // only node in the list if (last == NULL) { temp->info = data; temp->next = temp; last = temp; } // Else the new node will be the // last node and will contain // the reference of head node else { temp->info = data; temp->next = last->next; last->next = temp; last = temp; } } // Function to print the list void viewList() { // If list is empty if (last == NULL) printf("\nList is empty\n"); // Else print the list else { struct node* temp; temp = last->next; do { printf("\nData = %d", temp->info); temp = temp->next; } while (temp != last->next); } } // Driver Code int main() { // Function Call addatlast(); addatlast(); addatlast(); // Print list viewList(); return 0; }

Output:

Insertion after a specific element: Below is the program to insert a node after a specified node in the linked list.

C

// C program for the above operation #include <stdio.h> #include <stdlib.h> // Structure of a linked list node struct node { int info; struct node* next; }; // Pointer to last node in list struct node* last = NULL; // Function to add a new node // at the end of the list void addatlast() { // Stores number to be inserted int data; // Initialize a new node struct node* temp; temp = (struct node*)malloc(sizeof(struct node)); // Input data printf("\nEnter data to be inserted : \n"); scanf("%d", &data); // If the new node is the // only node in the list if (last == NULL) { temp->info = data; temp->next = temp; last = temp; } // Else the new node will be the // last node and will contain // the reference of head node else { temp->info = data; temp->next = last->next; last->next = temp; last = temp; } } // Function to insert after any // specified element void insertafter() { // Stores data and element after // which new node is to be inserted int data, value; // Initialize a new node struct node *temp, *n; // Input data printf("\nEnter number after which" " you want to enter number: \n"); scanf("%d", &value); temp = last->next; do { // Element after which node is // to be inserted is found if (temp->info == value) { n = (struct node*)malloc(sizeof(struct node)); // Input Data printf("\nEnter data to be" " inserted : \n"); scanf("%d", &data); n->info = data; n->next = temp->next; temp->next = n; // If temp is the last node // so now n will become the // last node if (temp == last) last = n; break; } else temp = temp->next; } while (temp != last->next); } // Function to print the list void viewList() { // If list is empty if (last == NULL) printf("\nList is empty\n"); // Else print the list else { struct node* temp; temp = last->next; do { printf("\nData = %d", temp->info); temp = temp->next; } while (temp != last->next); } } // Driver Code int main() { // Initialize the list addatlast(); addatlast(); addatlast(); // Function Call insertafter(); // Print list viewList(); return 0; }

Output:

Delete first element: Deleting the first node of the linked list. For this, the next pointer of last will point to the second node of the linked list. Below is the program for the same:

C

// C program for the above operation #include <stdio.h> #include <stdlib.h> // Structure of a linked list node struct node { int info; struct node* next; }; // Pointer to last node in list struct node* last = NULL; // Function to add a new node // at the end of the list void addatlast() { // Stores number to be inserted int data; // Initialize a new node struct node* temp; temp = (struct node*)malloc(sizeof(struct node)); // Input data printf("\nEnter data to be" " inserted: \n"); scanf("%d", &data); // If the new node is the only // node in the list if (last == NULL) { temp->info = data; temp->next = temp; last = temp; } // Else the new node will be the // last node and will contain // the reference of head node else { temp->info = data; temp->next = last->next; last->next = temp; last = temp; } } // Function to delete the first // element of the list void deletefirst() { struct node* temp; // If list is empty if (last == NULL) printf("\nList is empty.\n"); // Else last node now contains // reference of the second node // in the list because the // list is circular else { temp = last->next; last->next = temp->next; free(temp); } } // Function to print the list void viewList() { // If list is empty if (last == NULL) printf("\nList is empty\n"); // Else print the list else { struct node* temp; temp = last->next; do { printf("\nData = %d", temp->info); temp = temp->next; } while (temp != last->next); } } // Driver Code int main() { // Initialize the list addatlast(); addatlast(); addatlast(); // Function Call deletefirst(); // Print list viewList(); return 0; }

Output:

Delete the last element: Deleting the last node of the linked list. For this, the second last node will point to the first node of the list. Below is the program for the same:

C

// C program for the above operation #include <stdio.h> #include <stdlib.h> // Structure of a linked list node struct node { int info; struct node* next; }; // Pointer to last node in list struct node* last = NULL; // Function to add a new node // at the end of the list void addatlast() { // Stores number to be inserted int data; // Initialize a new node struct node* temp; temp = (struct node*)malloc(sizeof(struct node)); // Input data printf("\nEnter data to be inserted : \n"); scanf("%d", &data); // If the new node is the only // node in the list if (last == NULL) { temp->info = data; temp->next = temp; last = temp; } // Else the new node will be // last node and will contain // the reference of head node else { temp->info = data; temp->next = last->next; last->next = temp; last = temp; } } // Function to delete the last node // in the list void deletelast() { struct node* temp; // If list is empty if (last == NULL) printf("\nList is empty.\n"); temp = last->next; // Traverse the list till // the second last node while (temp->next != last) temp = temp->next; // Second last node now contains // the reference of the first // node in the list temp->next = last->next; last = temp; } // Function to print the list void viewList() { // If list is empty if (last == NULL) printf("\nList is empty\n"); // Else print the list else { struct node* temp; temp = last->next; do { printf("\nData = %d", temp->info); temp = temp->next; } while (temp != last->next); } } // Driver Code int main() { // Initialize the list addatlast(); addatlast(); addatlast(); // Function Call deletelast(); // Print the list viewList(); return 0; }

Output:

Delete at a given position: Delete an element from a specified position in the linked list. Below is the program for the same:

C

// C program for the above operation #include <stdio.h> #include <stdlib.h> // Structure of a linked list node struct node { int info; struct node* next; }; // Pointer to last node in list struct node* last = NULL; // Function to add a new node // at the end of the list void addatlast() { // Stores number to be inserted int data; // Initialize a new node struct node* temp; temp = (struct node*)malloc(sizeof(struct node)); // Input data printf("\nEnter data to be inserted : \n"); scanf("%d", &data); // If the new node is the // only node in the list if (last == NULL) { temp->info = data; temp->next = temp; last = temp; } // Else the new node will be // last node and will contain // the reference of head node else { temp->info = data; temp->next = last->next; last->next = temp; last = temp; } } // Function to delete an element // at a specified index in the list void deleteAtIndex() { // Stores the index at which // the element is to be deleted int pos, i = 1; struct node *temp, *position; temp = last->next; // If list is empty if (last == NULL) printf("\nList is empty.\n"); // Else else { // Input Data printf("\nEnter index : "); scanf("%d", &pos); // Traverse till the node to // be deleted is reached while (i <= pos - 1) { temp = temp->next; i++; } // After the loop ends, temp // points at a node just before // the node to be deleted // Reassigning links position = temp->next; temp->next = position->next; free(position); } } // Function to print the list void viewList() { // If list is empty if (last == NULL) printf("\nList is empty\n"); // Else print the list else { struct node* temp; temp = last->next; do { printf("\nData = %d", temp->info); temp = temp->next; } while (temp != last->next); } } // Driver Code int main() { // Initialize the list addatlast(); addatlast(); addatlast(); // Function Call deleteAtIndex(); // Print the list viewList(); return 0; }

Output:

Article Tags :

C Programs

Linked List

Technical Scripter

circular linked list

Linked Lists

Technical Scripter 2020

Practice Tags :

Linked List

circular linked list

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inserting a node at the end of a linked list

The new node will be added at the end of the linked list.

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Required knowledge

Basic C programming, Functions, Dynamic memory allocation, Circular linked list

Algorithm to insert a new node at the beginning of a Circular linked list

For inserting new node at the beginning of a circular linked list. We need to connect new node with the first node and re-connect the last node with new node instead of head node.

Algorithm to insert new node at the beginning of Circular linked list %%Input : head {Pointer to first node of the linked list} Begin If (head == NULL) then write ('List is empty') End if Else then alloc (newNode) read (data) newNode.data ← data; newNode.next ← head; current ← head; While (current.next != head) do current ← current.next; End while current.next ← newNode; End if End