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  1. #include <vector>
  2. #include <cstdlib>
  3. #include <iostream>
  4.  
  5. template <typename T>
  6. class Matrix_Proxy
  7. {
  8. public:
  9.     Matrix_Proxy(std::vector<T>& _ref, size_t _size) : ref(_ref), size(_size)
  10.     {}
  11.     T& operator[](int i)
  12.     {
  13.         return ref[i];
  14.     }
  15.  
  16.     const T& operator[](int i) const
  17.     {
  18.         return ref[i];
  19.     }
  20.  
  21. private:
  22.     std::vector<T>& ref;
  23.     size_t size;
  24.  
  25. };
  26.  
  27. template <typename T>
  28. class Matrix_Proxy_Const
  29. {
  30. public:
  31.     Matrix_Proxy_Const(const std::vector<T>& _ref, size_t _size) : ref(_ref), size(_size)
  32.     {}
  33.  
  34.     const T& operator[](int i) const
  35.     {
  36.         return ref[i];
  37.     }
  38.  
  39. private:
  40.     const std::vector<T>& ref;
  41.     size_t size;
  42.  
  43. };
  44.  
  45.  
  46. template <typename T>
  47. class Matrix
  48. {
  49. public:
  50.     Matrix(size_t x) : values(x), size(x)
  51.     {
  52.         for(auto&& y : values)
  53.         {
  54.             y.resize(x);
  55.             for(auto&& x : y)
  56.                 x = 0;
  57.         }
  58.     }
  59.  
  60.     Matrix_Proxy<T> operator [] (int i)
  61.     {
  62.         return Matrix_Proxy<T>(values[i],size);
  63.     }
  64.  
  65.     const Matrix_Proxy_Const<T> operator [] (int i) const
  66.     {
  67.         return Matrix_Proxy_Const<T>(values[i],size);
  68.     }
  69.  
  70. private:
  71.     std::vector<std::vector<T>> values;
  72.     size_t size;
  73. };
  74.  
  75. int main()
  76. {
  77.     Matrix<int> intMat(5);                    //FINE
  78.     std::cout << intMat[2][2] << std::endl;   //FINE
  79.  
  80.     const Matrix<int> cintMat(5);             //FINE
  81.     std::cout << cintMat[2][2] << std::endl;  //FINE
  82.  
  83. }
  84.  
Success #stdin #stdout 0s 3412KB
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https://ideone.com/HmlLfU
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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