Program To Create And Display A Singly Linked List

Explanation

In this program, we need to create a singly linked list and display all the nodes present in the list.

Singly Linked List

The singly linked list is a linear data structure in which each element of the list contains a pointer which points to the next element in the list. Each element in the singly linked list is called a node. Each node has two components: data and a pointer next which points to the next node in the list. The first node of the list is called as head, and the last node of the list is called a tail. The last node of the list contains a pointer to the null. Each node in the list can be accessed linearly by traversing through the list from head to tail.

Program to create and display a singly linked list

Consider the above example; node 1 is the head of the list and node 4 is the tail of the list. Each node is connected in such a way that node 1 is pointing to node 2 which in turn pointing to node 3. Node 3 is again pointing to node 4. Node 4 is pointing to null as it is the last node of the list.

Algorithm

Create a class Node which has two attributes: data and next. Next is a pointer to the next node.
Create another class which has two attributes: head and tail.
addNode() will add a new node to the list:
1. Create a new node.
2. It first checks, whether the head is equal to null which means the list is empty.
3. If the list is empty, both head and tail will point to the newly added node.
4. If the list is not empty, the new node will be added to end of the list such that tail’s next will point to the newly added node. This new node will become the new tail of the list.
display() will display the nodes present in the list:
1. Define a node current which initially points to the head of the list.
2. Traverse through the list till current points to null.
3. Display each node by making current to point to node next to it in each iteration.

Solution

Python

  #Represent a node of the singly linked list  class Node:      def __init__(self,data):          self.data = data;          self.next = None;            class SinglyLinkedList:      #Represent the head and tail of the singly linked list      def __init__(self):          self.head = None;          self.tail = None;                #addNode() will add a new node to the list      def addNode(self, data):          #Create a new node          newNode = Node(data);                    #Checks if the list is empty          if(self.head == None):              #If list is empty, both head and tail will point to new node              self.head = newNode;              self.tail = newNode;          else:              #newNode will be added after tail such that tail’s next will point to newNode              self.tail.next = newNode;              #newNode will become new tail of the list              self.tail = newNode;                    #display() will display all the nodes present in the list      def display(self):          #Node current will point to head          current = self.head;                    if(self.head == None):              print(“List is empty”);              return;          print(“Nodes of singly linked list: “);          while(current != None):              #Prints each node by incrementing pointer              print(current.data),              current = current.next;     sList = SinglyLinkedList();            #Add nodes to the list  sList.addNode(1);  sList.addNode(2);  sList.addNode(3);  sList.addNode(4);     #Displays the nodes present in the list  sList.display();  

Output:

 Nodes of singly linked list:   1 2 3 4

C

  #include <stdio.h>  #include <stdlib.h>  //Represent a node of singly linked list  struct node{      int data;      struct node *next;  };         //Represent the head and tail of the singly linked list  struct node *head, *tail = NULL;     //addNode() will add a new node to the list  void addNode(int data) {      //Create a new node      struct node *newNode = (struct node*)malloc(sizeof(struct node));      newNode->data = data;      newNode->next = NULL;            //Checks if the list is empty      if(head == NULL) {          //If list is empty, both head and tail will point to new node          head = newNode;          tail = newNode;      }      else {          //newNode will be added after tail such that tail’s next will point to newNode          tail->next = newNode;          //newNode will become new tail of the list          tail = newNode;      }  }     //display() will display all the nodes present in the list  void display() {      //Node current will point to head      struct node *current = head;            if(head == NULL) {          printf(“List is emptyn”);          return;      }      printf(“Nodes of singly linked list: n”);      while(current != NULL) {          //Prints each node by incrementing pointer          printf(“%d “, current->data);          current = current->next;      }      printf(“n”);  }        int main()  {      //Add nodes to the list      addNode(1);      addNode(2);      addNode(3);      addNode(4);            //Displays the nodes present in the list      display();         return 0;  }  

Output:

Nodes of singly linked list:   1 2 3 4

JAVA

  public class SinglyLinkedList {            //Represent a node of the singly linked list      class Node{          int data;          Node next;                    public Node(int data) {              this.data = data;              this.next = null;          }      }         //Represent the head and tail of the singly linked list      public Node head = null;      public Node tail = null;            //addNode() will add a new node to the list      public void addNode(int data) {          //Create a new node          Node newNode = new Node(data);                    //Checks if the list is empty          if(head == null) {              //If list is empty, both head and tail will point to new node              head = newNode;              tail = newNode;          }          else {              //newNode will be added after tail such that tail’s next will point to newNode              tail.next = newNode;              //newNode will become new tail of the list              tail = newNode;          }      }            //display() will display all the nodes present in the list      public void display() {          //Node current will point to head          Node current = head;                    if(head == null) {              System.out.println(“List is empty”);              return;          }          System.out.println(“Nodes of singly linked list: “);          while(current != null) {              //Prints each node by incrementing pointer              System.out.print(current.data + ” “);              current = current.next;          }          System.out.println();      }            public static void main(String[] args) {                    SinglyLinkedList sList = new SinglyLinkedList();                    //Add nodes to the list          sList.addNode(1);          sList.addNode(2);          sList.addNode(3);          sList.addNode(4);                    //Displays the nodes present in the list          sList.display();      }  }  

Output:

Nodes of singly linked list:   1 2 3 4

C#

   using System;                        public class CreateList  {      //Represent a node of the singly linked list      public class Node<T>{          public T data;          public Node<T> next;                    public Node(T value) {              data = value;              next = null;          }      }                public class SinglyLinkedList<T>{          //Represent the head and tail of the singly linked list          public Node<T> head = null;                        public Node<T> tail = null;                //addNode() will add a new node to the list          public void addNode(T data) {              //Create a new node              Node<T> newNode = new Node<T>(data);                 //Checks if the list is empty              if(head == null) {                  //If list is empty, both head and tail will point to new node                  head = newNode;                  tail = newNode;              }              else {                  //newNode will be added after tail such that tail’s next will point to newNode                  tail.next = newNode;                  //newNode will become new tail of the list                  tail = newNode;              }          }             //display() will display all the nodes present in the list          public void display() {              //Node current will point to head              Node<T> current = head;                            if(head == null) {                  Console.WriteLine(“List is empty”);                  return;              }              Console.WriteLine(“Nodes of singly linked list: “);              while(current != null) {                  //Prints each node by incrementing pointer                  Console.Write(current.data + ” “);                  current = current.next;              }              Console.WriteLine();          }      }            public static void Main()      {          SinglyLinkedList<int> sList = new SinglyLinkedList<int>();                    //Add nodes to the list          sList.addNode(1);          sList.addNode(2);          sList.addNode(3);          sList.addNode(4);                    //Displays the nodes present in the list          sList.display();          }  }  

Output:

Nodes of singly linked list:   1 2 3 4

PHP

  <!DOCTYPE html>  <html>  <body>  <?php  //Represent a node of singly linked list  class Node{      public $data;      public $next;            function __construct($data){          $this->data = $data;          $this->next = NULL;      }  }  class SinglyLinkedList{      //Represent the head and tail of the singly linked list      public $head;      public $tail;      function __construct(){          $this->head = NULL;          $this->tail = NULL;      }            //addNode() will add a new node to the list      function addNode($data) {          //Create a new node          $newNode = new Node($data);                    //Checks if the list is empty          if($this->head == NULL) {              //If list is empty, both head and tail will point to new node              $this->head = $newNode;              $this->tail = $newNode;          }          else {              //newNode will be added after tail such that tail’s next will point to newNode              $this->tail->next = $newNode;              //newNode will become new tail of the list              $this->tail = $newNode;          }      }            //display() will display all the nodes present in the list      function display() {          //Node current will point to head          $current = $this->head;                    if($this->head == NULL) {              print(“List is empty <br>”);              return;          }          print(“Nodes of singly linked list: <br>”);          while($current != NULL) {              //Prints each node by incrementing pointer              print($current->data . ” “);              $current = $current->next;          }          print(“<br>”);      }  }        $sList = new SinglyLinkedList();            //Add nodes to the list  $sList->addNode(1);  $sList->addNode(2);  $sList->addNode(3);  $sList->addNode(4);     //Displays the nodes present in the list  $sList->display();  ?>  </body>  </html>  

Output:

 Nodes of singly linked list:   1 2 3 4

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Program To Create And Display A Singly Linked List