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  1. #include <array>
  2. #include <iostream>
  3. #include <vector>
  4.  
  5. using vector3d = std::array<double, 3>;
  6.  
  7. class field
  8. {
  9. public:
  10. 	// the explicit prevents std::size_t's to be implicitely cast into fields ;-)
  11. 	explicit field(std::size_t size)
  12. 		: vectors_(size)
  13. 	{
  14. 	}
  15.  
  16. 	vector3d & operator[] (std::size_t index) { return vectors_[index]; }
  17. 	vector3d operator[] (std::size_t index) const { return vectors_[index]; }
  18.  
  19. private:
  20. 	// this is pretty contigous
  21. 	std::vector<vector3d> vectors_;
  22. };
  23.  
  24. int main()
  25. {
  26.     field f(2);
  27.     vector3d & v = f[1];
  28.     v[2] = 5;
  29.  
  30. 	// also: this is a copy of v, so changing v2 will not affect f[1][2]
  31.     vector3d v2 = v;
  32.     v2[2] = 2;
  33.  
  34.     std::cout << f[1][2] << std::endl;
  35.  
  36.     return 0;
  37. }
Success #stdin #stdout 0s 3228KB
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5
https://ideone.com/o740je
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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