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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. class Variable {
  5. 		virtual void display() { cout <<"Oops, try to display variable ..."<<endl; }
  6. };
  7. class Number : public Variable {};
  8. class Boolean : public Variable {};
  9. class RealNumber : public Number {};
  10. class IntegerNumber : public Number {
  11. protected:
  12. 	int val; 
  13. public: 
  14. 	IntegerNumber(int v=0): val(v) {}
  15. 	void display() override { cout <<"Display integer "<<val<<endl; }
  16. 	};
  17.  
  18. class Virtuality  { 
  19. public:
  20. 	virtual void compute_virtual_value() { cout <<"I compute my virtual value...\n"; }
  21. 	};     
  22. class VirtualVariable : public Variable, public Virtuality  {};
  23. class VirtualNumber : public Number, public Virtuality  {};
  24. class VirtualBoolean : public Boolean, public Virtuality  {};
  25. class VirtualRealNumber : public RealNumber, public Virtuality  {};
  26. class VirtualIntegerNumber : public IntegerNumber, public Virtuality  {
  27. public:
  28. 	void compute_virtual_value() override { cout <<"I compute my virtual INTEGER value...\n"; val=1000; }
  29. 	void display() override { 
  30. 		compute_virtual_value(); 
  31. 		cout <<"....Display virtual integer "<<val<<endl; 
  32. 	}
  33. };
  34.  
  35. IntegerNumber add (IntegerNumber &a, IntegerNumber&b) {
  36. 	cout << "add:\n"; 
  37. 	cout << "   "; a.display(); 
  38. 	cout << "   "; b.display(); 
  39. 	return IntegerNumber(-1);   // ok, must be elaborated a little bit more here ;-)
  40. }
  41.  
  42. int main() {
  43. 	IntegerNumber n(27);  // number with an inital value
  44. 	VirtualIntegerNumber k;   // value will be calculated from some formula 
  45. 	add (n, k);
  46.  
  47. 	return 0;
  48. }
Success #stdin #stdout 0s 3144KB
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Standard input is empty
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add:
   Display integer 27
   I compute my virtual INTEGER value...
....Display virtual integer 1000
https://ideone.com/ZoaE2a
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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