Linked lists and return value for + Operator overloading

[yousbj]

The assignment is to make a linked list class that represents a polynomial. Each node represents one term. Then we have to overload the + operator in order to do the sum of two polynomial. I also overloaded the = operator to create a deep copy of a polynomial and the << operator to display the polynimial.
My probem is within the + operator. This is my code:

Poly Poly::operator+(const Poly& orig)
{
Poly n;
polyTerm* cur;
polyTerm* cur2;
cur=head;
cur2=orig.head;
//Add all the terms from the Left Hand polynomial
while(cur != NULL)
{
n.newterm(cur->exponent, cur->coefficient);
cur = cur->next;
}

//Add all the terms from the Right Hand polynomial
while(cur2 != NULL)
{
n.newterm(cur2->exponent, cur2->coefficient);
cur2 = cur2->next;
}
n.sort(); //sort terms in descending order of exponents
n.simplify();//combine terms with equal exponents into a single term by addition
cout<<"\nFinal sum is: "<<endl<<n;
return n;
}


The line right above the return proves that the operation has succeeded since it displays the correct polynomial. However, in the main function when I do sum=Poly1+Poly2,and cout<<sum it displays only the first term of the sum polynomial.
After investigation I think the problem comes from the " return n" in the + overloading.

Could anyone help me find the problem please ?

[MiiNiPaa]

You didn't provide a copy constructor Poly::Poly(const Poly& original), so it makes an shallow copy. You also should write destructor.
http://en.wikipedia.org/wiki/Rule_of_three_%28C%2B%2B_programming%29

[CroCo]

This topic is deriving me crazy.