Question

In my “void union” function I am unsure how to insert the data from both linked lists “A” and “B” that the user has input respectively since the “AUB” is not within the void function. I would have put:

AUB.insert

but I was unsure. Any suggestions?

#include "stdafx.h"
#include <iostream>

using namespace std;

class Sets
{
private:struct NODE
        {
            int info;
            NODE *next;
        };
        NODE *list;
public:Sets()
       {
           list=NULL;
       }
       void Insert(int x)
       {
           NODE *p=list, *q=list, *r;
           //create a new node
           r = new (NODE);
           r->info = x;
           r->next = NULL;
           //find the insertion place
           while(p != NULL && p->info < x)
           {
               q=p;
               p=p->next;
           }
           if(p==list)//x is the first info
           {
               list=r;
               r->next=p;
           }
           else if(p==NULL)//x is the last info
           {
               q->next=r;
           }
           else //x is neither forst nor last info
           {
               r->next=p;
               q->next=r;
           }
       }
        void display()
        {
            NODE *p=list;
            while(p != NULL)
            {
                cout << p->info << "-->";
                p=p->next;
            }
            cout << "NULL\n";
        }
        void Union(Sets setA,Sets setB)
        {
            NODE *p=setA.list, *q=setB.list;
            while(p != NULL && q != NULL)
            {
                if(p->info > q-> info)
                {
                    (q->info)
                    q=q->next;
                }
                else if(p->info == q->info)
                {
                    insert(p->info)
                    p=p->next;
                    q=q->next;
                }
                else//P->info < q->info
                {
                    insert(p->info);
                    p=p->next;
                }
            }
            while(p !=NULL)
            {
                insert(p->info);
                p=p->next;
            }
            while(q != NULL)
            {
                insert(q->info);
                q=q->next;
            }
        }
};


int main()
{   
    //create a set of integers
    int x;
    Sets A, B, setAUB;
    cout << "Enter data for setA:\n";
    cout << "Enter a group of positive integer numbers with -1 at the end end: ";
    cin >> x;
    while(x != -1)
    {
        A.Insert(x);
        cin >> x;
    };
    //display setA
    cout << endl << "setA=";
    A.display();

    cout << "Enter data for setB:\n";
    cout << "Enter a group of positive integer numbers with -1 at the end end: ";
    cin >> x;
    while(x != -1)
    {
        B.Insert(x);
        cin >> x;
    };
    //display setB
    cout << endl << "setB=";
    B.display();

    setAUB.Union(A, B);
    //display setAUB
    cout << endl << "setAUB=";
    setAUB.display();

    system ("pause");

    //terminate program
    return 0;
}; 

Answer 1

You define it: void Union(Sets setA,Sets setB).

What are you doing? Both passed by value, and the return value is void – where does the result go?

Does your current object (this in the Union function) become that union? If so, what happens to the data already in it? You’re not deleting it, so you’re basically merging three sets, not two…

I would suggest to create a static merge function that would take the two parameters and return a new list which would be the merge of the two.

Otherwise, create a regular merge function, that would only take 1 parameter, and merge it into the current object.

By the way – why Sets, when it is obviously a sorted linked list?