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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. struct parent
  5. {
  6.     virtual ~parent() = default;
  7.     virtual void foo() = 0;
  8. };
  9.  
  10. struct Child : parent
  11. {
  12. 	Child(int n) : n(n) {}
  13.     void foo() override { std::cout << n << std::endl; }
  14. 	int n;
  15. };
  16.  
  17. class Grid{
  18. public:
  19.     Grid() : col(10), row(10), grid(col * row, nullptr) {}
  20.  
  21.     parent* operator() (std::size_t x, std::size_t y) const {
  22.         if (col <= x || row <= y) { throw std::runtime_error("Invalid arguments"); }
  23.         return grid[y * col + x];
  24.     }
  25.  
  26.     parent*& operator() (std::size_t x, std::size_t y) {
  27.         if (col <= x || row <= y) { throw std::runtime_error("Invalid arguments"); }
  28.         return grid[y * col + x];
  29.     }
  30.  
  31. private:
  32.     int col;
  33.     int row;
  34.     std::vector<parent*> grid;
  35. };
  36.  
  37.  
  38. int main() {
  39. 	Grid b;
  40. 	Child c(1);
  41. 	Child c2(2);
  42.  
  43. 	b(1,1) = &c;
  44. 	b(1,4) = &c2;
  45.  
  46. 	b(1,1)->foo(); //calls the first Childs foo()
  47. 	b(1,4)->foo(); //calls the second Childs foo()
  48. }
Success #stdin #stdout 0s 15240KB
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https://ideone.com/QUZQGF
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

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