How to delete a node in a linked list?

Question

This is what I have so far, but it\'s not working in the test file. Basically skips to the else if(cnode == preposition)

void LinkedList::Delete(Nod         


        

Answer 1

Three cases of delete in a singly linked-list:

1. delete the first node

   void delete_first()
   {
       node *temp=new node;
       temp=head;
       head=head->next;
       delete temp;
   }
   

2. delete the last node

   void delete_last()
   {
       node *current = new node;
       node *previous = new node;
       current=head;
       while(current->next != NULL)
       {
         previous = current;
         current = current->next;  
       }
       tail = previous; // if you have a Node* tail member in your LinkedList
       previous->next = NULL;
       delete current;
   }
   

3. delete at a particular position (your case)

   void LinkedList::delete_position(int pos)
   {
       node *current=new node;
       node *previous=new node;
       current=head;
       for(int i=1; i < pos; i++) //or i = 0; i < pos-1
       {
          previous=current;
          current=current->next;
       }
       previous->next=current->next;
       delete current;
   }
   

   ^^ from codementor ^^

However if your function signature intends delete_node(Node* nodeToDelete) [PrePosition is not a good name in this case] and you want delete the node passed to the function without knowing its position in the list we can modify delete_position() like so:

void LinkedList::delete_node(Node* nodeToDelete)
{
    node *current= head;
    node *previous= nullptr;

    if (head == nodeToDelete){
        head = nodeToDelete->next;
        delete nodeToDelete;
        return
    }//else
    while(current != nodeToDelete)
    {
        previous = current;
        current = current->next
    }
    previous->next = current->next;
    delete nodeToDelete;
}

Also in your original code, if it's skipping the line you mentioned, pnode is always null when cnode has a non-null value in it.