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  1. #include <cstdint>
  2. #include <iostream>
  3. #include <algorithm>
  4. #include <vector>
  5.  
  6. template <typename T>
  7. class Matrix
  8. {
  9.     public:
  10.         Matrix(std::size_t rows, std::size_t columns);
  11.         Matrix(std::initializer_list<std::initializer_list<T>> init);
  12.         auto rows() const -> std::size_t;
  13.         auto columns() const -> std::size_t;
  14.         auto operator()(std::size_t i, std::size_t j) const -> const T&;
  15.         auto operator()(std::size_t i, std::size_t j) -> T&;
  16.     private:
  17.         const std::size_t rows_;
  18.         const std::size_t columns_;
  19.         std::vector<T> elements_;
  20.  
  21. };
  22.  
  23. template <typename T>
  24. Matrix<T>::Matrix(std::size_t rows, std::size_t columns)
  25. : rows_{ rows }, columns_{ columns }, elements_( rows * columns )
  26. {
  27. }
  28.  
  29. template <typename T>
  30. Matrix<T>::Matrix(std::initializer_list<std::initializer_list<T>> init)
  31. : Matrix{ 
  32.     init.size(),
  33.     std::max(
  34.         init,
  35.         [](const auto& a, const auto& b) {
  36.             return a.size() < b.size();
  37.         }
  38.     ).size()
  39.   }
  40. {
  41.     std::size_t i = 0;
  42.     for (const auto& row : init)
  43.     {
  44.         if (i >= rows())
  45.             break;
  46.         std::size_t j = 0;
  47.         for (const auto& value : row)
  48.         {
  49.             if (j >= columns())
  50.                 break;
  51.             (*this)(i, j) = value;
  52.             ++j;
  53.         }
  54.         ++i;
  55.     } 
  56. }
  57.  
  58. template <typename T>
  59. auto Matrix<T>::rows() const -> std::size_t
  60. {
  61.     return rows_;
  62. }
  63.  
  64. template <typename T>
  65. auto Matrix<T>::columns() const -> std::size_t
  66. {
  67.     return columns_;
  68. }
  69.  
  70. template <typename T>
  71. auto Matrix<T>::operator()(std::size_t i, std::size_t j) const -> const T&
  72. {
  73.     return elements_[ i * columns() + j];
  74. }
  75.  
  76. template <typename T>
  77. auto Matrix<T>::operator()(std::size_t i, std::size_t j) -> T&
  78. {
  79.     return elements_[ i * columns() + j];
  80. }
  81.  
  82. template <typename T>
  83. std::ostream& operator<<(std::ostream& out, const Matrix<T>& m)
  84. {
  85.     out << typeid(T).name() << m.rows() << "x" << m.columns();
  86.     out << "{ ";
  87.     for (std::size_t i = 0; i < m.rows(); ++i)
  88.     {
  89.         if (i > 0)
  90.             out << ", ";
  91.         out << "{ ";
  92.         for (std::size_t j = 0; j < m.columns(); ++j)
  93.         {
  94.             if (j > 0)
  95.                 out << ", ";
  96.             out << m(i, j);
  97.         }
  98.         out << " }";
  99.     }
  100.     out << " }";
  101.     return out;
  102. }
  103.  
  104. auto main() -> int
  105. {
  106.     Matrix<float> m
  107.     {
  108.         { 1, 2, 3 },
  109.         { 4, 5, 6 },
  110.         { 7, 8, 9 }
  111.     };
  112.  
  113.     std::cout << m << std::endl;
  114. }
Success #stdin #stdout 0s 4280KB
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Standard input is empty
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f3x3{ { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } }
https://ideone.com/hX3l5T
language:
C++14 (clang 8.0)
created:
4 years ago
visibility:
public

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