#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);
        void Readin();
        void Printout();
        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);
    }
    
    
    void SL::Printout() // Printing out the contents of a SL
    {
       if (ptr == 0)
          {cout << "data " << " 0 value none int " << val << endl; return;}
       cout << "data " << ptr << " value " << *ptr << " int " << val << endl;
       return;
    }
    
    void SL::Readin()  // Reading in the contents of a SL
    { cout << "Input two values" << endl;
      ptr = new int;
      cin >> *ptr >> val;
    }
    
    void SL::Erase() {
       delete(ptr);
       ptr=0;
    }
    #include "listNode.h"
    
    int main()
    {
      cout << endl;
    
      SL l;    // A80
      l.Readin();
      cout << "SL l" << " Located at " << &l << endl;
      l.Printout();
      cout << endl;
       //  A80   A08    4    3
    
      SL m;    //  A70
      m.Readin();
      cout << "SL m"  << " Located at " << &m<< endl;
      m.Printout();
      cout << endl;
       //  A70  A18   2    1
    
      SL o = m;    //  A60
    //  There is a correct copy constructor so it works
      cout << "SL o"  << " Located at " << &o<< endl;
      o.Printout();
      cout << endl;
       //  Copy from A70  A60
       //  A60   A28   2   1
    
      SL q;  // A50
    //  Works just fine
      q = m;
      cout << "SL q"  << " Located at " << &q<< endl;
      q.Printout();
      cout << endl;
       //  Assign from A70  to A50
       //  Copy   from A50  to A40
       //  Destroy  A40
       // A50   A38   2   1
    
      l.Erase();
      m.Erase();
    
      cout << "SL l"  << " Located at " << &l<< endl;
      l.Printout();
       //  A80   A0    --    3
      cout << "SL m"  << " Located at " << &m<< endl;
      m.Printout();
       //  A70  A0     --    1
      cout << "SL o"  << " Located at " << &o<< endl;
      o.Printout();
       //  A60   A28   2   1
      cout << "SL q"  << " Located at " << &q<< endl;
      q.Printout();
       // A50   A38   2   1
    
      cout << endl;
     
      SL r,s;  //A40   A30
    // Will also work
      r = s = q;
        //  Assignment from A50 to A30
        //  Copy from A30 to A10
        //  Assignment from A10 to A40
        //  Copy from A40 to A20
        //  Dealloc   A20
        //  Dealloc   A10
    
      cout << "SL s"  << " Located at " << &s<< endl;
      s.Printout();
        // A30  A18   2  1
      cout << "SL r"  << " Located at " << &r<< endl;
      r.Printout();
        // A40  A58  2  1
      cout << "SL q"  << " Located at " << &q<< endl;
      q.Printout();
        // A50  A38  2   1
      cout << endl;
    
    
      return 0;
    }