overloading + operator in a polynomial linked list

Question

so i am trying to overload the + operator in a single linked list the problem is that my program crashes each time i try to run the code.in my code i tried to add the coefficients with the same exponent.And in case the exponents are not equal i tried to add the different two terms to the resulting polynomial. The insert function adds the term in a sorted order from higher exponent to lower one

 polynomials polynomials:: operator + (const polynomials&p )const{
 node*current=head;
 node*temp=p.head;
 polynomials poly;
 node *newnode=0;
 while(current!=0||temp!=0)
 {
    if(current->exponent==temp->exponent)
    {
       newnode->exponent=current->exponent;
        newnode->coefficient=current->coefficient+temp->coefficient;
        poly.insert(*newnode);
        newnode=newnode->link;
    }
    else
    {
        if(current->exponent > temp->exponent)
      { newnode->exponent=current->exponent;
        newnode->coefficient=current->coefficient;
        poly.insert(*newnode);
        newnode=newnode->link;    
        newnode->exponent=temp->exponent;
        newnode->coefficient=temp->coefficient;
        poly.insert(*newnode);
        }
        else
        {

        newnode->exponent=temp->exponent;
        newnode->coefficient=temp->coefficient;
        poly.insert(*newnode);
        newnode=newnode->link;    
        newnode->exponent=current->exponent;
        newnode->coefficient=current->coefficient;
        poly.insert(*newnode);


        }

    }
    current=current->link;
    temp=temp->link;
 }

 return poly;}

Answer 1

One problem I see.

while(current!=0||temp!=0) 

followed by

if(current->exponent==temp->exponent)

is not right. If one of the pointers is nullptr , you end up dereferencing a nullptr .

I would try

while(current != nullptr && temp != nullptr)