#include <iostream>
    
    using namespace std;
    
    // Definition for Class SL
    class SL {
    private: // Each object contains two values
        int *ptr;  // Pointer to int
        int val;   // Just an int
    public: // Member functions
        SL();
        ~SL();
        SL(const SL &);
        SL SL::operator=(const SL & fr);
        friend ostream & operator<<(ostream & os, const SL &);
        friend istream & operator>>(istream &, SL &);
        SL SL::operator+(const SL &);
        void Erase();
    };
    
    // Constructor for Class SL
    SL::SL()
    {ptr = 0;
     cout << "allocated SL " << this << endl;
    }
    
    SL::~SL()
    {cout << "deallocated SL " << this << endl;
     this->Erase();}
    
    // Copy Constructor for Class SL
    SL::SL(const SL & fr)
    {cout << "Copy Constructructor from SL " << &fr << " to SL " << this << endl;
       this->val = fr.val;
       this->ptr = 0;
       if (fr.ptr)
          {ptr = new int;
           *ptr = *(fr.ptr);
          }
       return;
    }
    
    SL SL::operator=(const SL & fr){
       cout << "Assignment Operator from SL " << &fr << " to SL " << this << endl;
       // Avoiding potential Memory Leak here.
       if (this == &fr) return (fr);
       this->val = fr.val;
       this->ptr = 0;
       if (fr.ptr)
          {ptr = new int;
           *ptr = *(fr.ptr);
          }
       return (*this);
    }
    
    ostream & operator<<(ostream & os, const SL & fr)
    {   if (fr.ptr == 0)
          {os << "data " << " 0 value none int " << fr.val << endl; return os;}
       os << "data " << fr.ptr << " value " << *(fr.ptr) << " int " << fr.val << endl;
       return os;
    }
    
    istream & operator>>(istream & is, SL & fr)
    { int contents;
      cout << "Input two values" << endl;
      fr.ptr = new int;
      is >> *(fr.ptr) >> fr.val;
      return is;
    }
    
    SL SL::operator+(const SL & fr){
       cout << "Addition Operator for List " << &fr << " to List " << this <<
    endl;
       SL t;
       t.val = fr.val + this->val;
       t.ptr = new int;
       *(t.ptr)=0;
       if (fr.ptr != 0) *(t.ptr)=*(t.ptr) +*(fr.ptr);
       if (this->ptr != 0) *(t.ptr)=*(t.ptr) +*(this->ptr);
       return t;
    }
    
    void SL::Erase() {
       delete(ptr);
       ptr=0;
    }
    
    #include "listNode.h"
    
    int main()
    {
      cout << endl;
    
      SL l;   // 8e0
      cin >> l;
      cout << "SL l" << " Located at " << &l << endl;
      cout << l;
      cout << endl;
        //   8e0   008     4   3
    
      SL m;  // 8d0
      cin >> m;
      cout << "SL m"  << " Located at " << &m<< endl;
      cout << m;
      cout << endl;
    
         // 8d0    018   2   1
    
      SL q;   //  8c0
    //  Works just fine
      q = l + m;
      cout << "SL q"  << " Located at " << &q<< endl;
      cout << q;
      cout << endl;
         //  Add 8d0   and 8e0
         //  Alloc 8a0
         //  Assign  8a0 to 8c0
         //  Copy  8c0  to 8b0
         // Dealloc  8b0
         // Dealloc  8a0
         //  8c0   038   6   4
    
      l.Erase();
      m.Erase();
    
      cout << "SL l"  << " Located at " << &l<< endl;
      cout << l;
        //   8e0   0     ---   3
      cout << "SL m"  << " Located at " << &m<< endl;
      cout << m;
        //   8d0   0     ---   1
      cout << "SL q"  << " Located at " << &q<< endl;
      cout << q;
         //  8c0   038   6   4
    
      cout << endl;
    
      return 0;
    }