Deletion in Singly Linked List at Beginning

by Online Tutorials Library July 22, 2022

Deletion in singly linked list at beginning

Deleting a node from the beginning of the list is the simplest operation of all. It just need a few adjustments in the node pointers. Since the first node of the list is to be deleted, therefore, we just need to make the head, point to the next of the head. This will be done by using the following statements.

Now, free the pointer ptr which was pointing to the head node of the list. This will be done by using the following statement.

Algorithm

Step 1: IF HEAD = NULL

Write UNDERFLOW
Go to Step 5
[END OF IF]

Step 2: SET PTR = HEAD
Step 3: SET HEAD = HEAD -> NEXT
Step 4: FREE PTR
Step 5: EXIT

C function

  #include<stdio.h>  #include<stdlib.h>  void create(int);  void begdelete();  struct node  {  int data;  struct node *next;  };  struct node *head;  void main ()  {  int choice,item;  do   {  printf(“n1.Append Listn2.Delete noden3.Exitn4.Enter your choice?”);  scanf(“%d”,&choice);  switch(choice)  {  case 1:  printf(“nEnter the itemn”);  scanf(“%d”,&item);  create(item);  break;   case 2:  begdelete();  break;   case 3:  exit(0);  break;  default:  printf(“nPlease enter valid choicen”);  }    }while(choice != 3);  }  void create(int item)  {  struct node *ptr = (struct node *)malloc(sizeof(struct node *));  if(ptr == NULL)  {  printf(“nOVERFLOWn”);  }  else  {  ptr->data = item;  ptr->next = head;  head = ptr;  printf(“nNode insertedn”);  }    }  void begdelete()  {  struct node *ptr;  if(head == NULL)  {  printf(“nList is empty”);  }  else   {  ptr = head;  head = ptr->next;  free(ptr);  printf(“n Node deleted from the begining …”);  }  }  

Output

1.Append List  2.Delete node  3.Exit  4.Enter your choice?1    Enter the item  23    Node inserted    1.Append List  2.Delete node  3.Exit  4.Enter your choice?2     Node deleted from the begining ...

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Deletion in Singly Linked List at Beginning

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