Question

3. Suppose you have a linked list structure and a node structure defined as follows:
template <class T>
class llist {
lnode<T> *header;
llist() {
header = new lnode<T>(T());
header->prev = header;
header->next = header;
}
void eraseAll(const T& target);
};

template <class T>
struct lnode {
T val;
lnode<T>* next;
lnode<T>* prev;
lnode(const T& x, lnode<T>* y=NULL,
lnode<T>* z=NULL) : val(x),
next(y), prev(z) {}
};

Write the llist member function eraseAll, which takes a value target and erases all occurrences of target
in the list.

Answer 1

//3
void eraseAll(const T& target)
{
   lnode<T> *temp = header;//to traverse the list
  
   while(temp!=NULL)
   {
      
       if(temp->val == target)   //if found then delinking that node
       {
           if(temp->prev!=NULL)//if previous node is not null
           {
               temp->prev=temp->next;//removing middle node
                  
           }
           else//means it is the first node
           {
               //so
               header= head->next;//removing first node
              
           }
          
          
       }
      
       temp=temp->next;
   }
  
}