A Program For Binary Calculation in C++

#include<iostream.h>
#include<conio.h>
class binary_calculation
{
  protected :
    float x;
    float y;

  public :
    virtual float calculate()
    {
      cout<<"Please enter 1 to 4 as your option";
      cin.get();
      return (0);
    }
    void getdata()
    {
      cout<<"Enter the numebrs ";
      cin>>x>>y;
    }
};
class addition :public binary_calculation
{
  float calculate()
  {
    return (x+y);
    }
  };
class subtraction : public binary_calculation
{
  float calculate ()
  {
    return (x-y);
  }
};
class multiplication : public binary_calculation
{
  float calculate ()
  {
    return (x*y);
  }
};
class division : public  binary_calculation
{
  float calculate ()
  {
    return (x/y);
  }
};
main()
{
  binary_calculation *p;
  addition A;
  subtraction S;
  multiplication M;
  division D;
  clrscr();
  int opt;
  float result;
  cout<<"1-Addition"<<endl
  <<"2-Subtractio"<<endl
  <<"3-Multiplication"<<endl
  <<"4-Division"<<endl
  <<"Your option";
  cin>>opt;
  switch (opt)
  {
   case 1 :
   p=&A;
   break;
   case 2 :
   p=&S;
   break;
   case 3 :
   p=&M;
   break;
   case 4 :
   p=&D;
   break;
  }
  if (opt>4)
   result = p->binary_calculation::calculate();
  else
  {
    p->getdata();
    result=p->calculate();
    cout<<"Result = "<<result;
  }
  getch();
}