Returning a new object

[JRimmer]

The purpose of the below function is to copy the information of the caller, and the information of the object on the Right Hand Side. Then return a combination of the two, without repeats. (Set Union)

I believe my code is working as far as copying the two Set objects, but when I return I'm returning a temporary address that once the function has completed running, goes out of scope. Which in turn causes my = operator to fail.

Is there a way to get around this?

As a part of this assignment I am not allowed to modify S1 (the caller) or S2 (the object being called).

I've overloaded the = operator, as well as the << operator. I've tested those and they work for sure.

Call inside the Main.cpp

//Store the results of S1 + S2 inside S3
S3 = S1+S2;
cout << S3;

Implementation in the Set.cpp file

  Set & Set::operator+(Set &obj){
	Set newList;
	ListNode *newNode;
	ListNode *nLhere = newList.head->next;
	ListNode *nLprev = newList.head;

	ListNode *objhere = obj.head->next;
	ListNode *objprev = obj.head;

	ListNode *here = this->head->next;
	ListNode *prev = this->head;

	//Copy Elements of List 1 into newList;
	while (here->next != NULL){
		newNode = new ListNode(here->integer);
		nLprev->next = newNode;
		newNode->next = nLhere;

		prev = here;
		here = here->next;

		nLprev = nLprev->next;
		nLhere = newNode->next;
	}

	//Copy Elements of List 2 into newList;
	while (objhere->next != NULL){
		if (!newList.find(objhere->integer))
		{
			newList.Insert(objhere->integer);
		}

		objprev = objhere;
		objhere = objhere->next;
	}

        //Returning a temporary variable, bad idea, need a new one
	return newList;
}

Thanks for taking a look!

[LB]

Remove the first, but not the second, ampersand on line 1. Prior to C++11, copy-elision is a common compiler optimization. After C++11, move semantics will take care of it for you.

By the way, the parameter and the function itself should be const.

[JRimmer]

Problem solved. Thank you.