#include <iostream.h> 

class Xyz
{  public:
     Xyz(int& a, int b)   // constructor
     : abc(a), ijk(b) {}  // must initialize
     //void uvw(int& u, int v)
     //{  this->Xyz(u,v); }   illegal
     void display()
     { cout << abc << " " << ijk << endl; }
     void increment() { abc += ijk; }
   private:
     int& abc;            // reference member
     const int ijk;       // const member
};

int main()
{   int u = 1, v = 20, w = 99, z = 500;
    Xyz r(u,v), s(w, z);
    r.display(); s.display();
    r.increment();  s.increment();
    r.display(); s.display();
    cout << "Now u = " << u
         << ", w = " << w << endl;
    //r.uvw(v,z);
    // r.Xyz(v,z);    // re-initialize r  illegal
    return(0);
}