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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. class my_vector {
  5. public:
  6. 	double data[6] = {1,2,3,4,5,6};
  7. 	double & operator()(size_t i) {
  8. 		std::cout<<"Calling non-const ()"<<std::endl;
  9. 		return data[i];
  10. 	}
  11. 	double operator()(size_t i) const {
  12. 		std::cout<<"Calling const ()"<<std::endl;
  13. 		return data[i];
  14. 	}
  15. };
  16.  
  17. void withConst(const my_vector &v) {
  18. 	double vv = v(0);
  19. 	std::cout<<"v(0) = "<<vv<<std::endl;
  20. 	// v(0) = 4.0; // Does not compile
  21. }
  22.  
  23. void withNonConst(my_vector &v) {
  24. 	v(0) = 4.0;
  25. 	double vv = v(0);
  26. 	std::cout<<"v(0) = "<<vv<<std::endl;
  27. }
  28.  
  29. int main() {
  30. 	my_vector vec;
  31. 	withConst(vec);
  32. 	withNonConst(vec);
  33. 	return 0;
  34. }
Success #stdin #stdout 0s 3468KB
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Standard input is empty
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Calling const ()
v(0) = 1
Calling non-const ()
Calling non-const ()
v(0) = 4
https://ideone.com/kO0Rf1
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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