C Program for Insertion at the End of the Singly Linked List

#include<stdio.h>
#include<stdlib.h>

struct Node
{
  int data;
  struct Node *next;
};

void insertEnd (struct Node **head, int data)
{

  // since this will be the last node so it will point to NULL
  struct Node *newNode = (struct Node *) malloc (sizeof (struct Node));
  newNode->data = data;
  newNode->next = NULL;

  // if Linked List is empty its is first node being entered
  if (*head == NULL)
    {
      *head = newNode;
      return;
    }
  // otherwise find the current last node

  // create another variable to traverse the LL
  // *head should not be used as we do not want to change head
  struct Node *temp = *head;

  // traverse to the last node of Linked List
  while (temp->next != NULL)
    temp = temp->next;

  // assign last node's next to this newNode
  temp->next = newNode;

  printf ("%d inserted at the end\n", data);
}


void display (struct Node *node)
{

  // as linked list will end when Node is Null
  while (node != NULL)
    {
      printf ("%d ", node->data);
      node = node->next;
    }
  printf ("\n");
}

int
main ()
{
  //creating 4 pointers of type struct Node
  //So these can point to address of struct type variable
  struct Node *head = NULL;
  struct Node *node2 = NULL;
  struct Node *node3 = NULL;
  struct Node *node4 = NULL;

  // allocate 3 nodes in the heap 
  head = (struct Node *) malloc (sizeof (struct Node));
  node2 = (struct Node *) malloc (sizeof (struct Node));
  node3 = (struct Node *) malloc (sizeof (struct Node));
  node4 = (struct Node *) malloc (sizeof (struct Node));

  head->data = 22;		// data set for head node 
  head->next = node2;		// next pointer assigned to address of node2 

  node2->data = 30;
  node2->next = node3;

  node3->data = 24;
  node3->next = node4;

  node4->data = 20;
  node4->next = NULL;

  /*No need for & i.e. address as we do not
     need to change head address
   */
  printf ("Linked List Before Operations : ");
  display (head);

  insertEnd (&head, 5);
  insertEnd (&head, 6);
  insertEnd (&head, 7);
  insertEnd (&head, 8);

  printf ("Linked List After Operations : ");
  display (head);

  return 0;
}