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  1. #include <iostream>
  2. #include <memory>
  3.  
  4. class Matrix {
  5. private:
  6.   int row;
  7.   int column;
  8.   std::shared_ptr<double> content;
  9. public:
  10.  
  11.   Matrix() : row(0), column(0), content(nullptr) {}
  12.  
  13.   template<class... A> void set(int row, int column, A... args) {
  14.     double *array_content = new double[row * column];
  15.     double *p = array_content;
  16.     int n = 0;
  17.     for (double x : std::initializer_list<double>{args...}) {
  18.       *p = x;
  19.       p++; n++;
  20.     }
  21.     while (n < row * column) {
  22.       *p = 0.0;
  23.       p++; n++;
  24.     }
  25.     this->content.reset(array_content);
  26.     this->row = row;
  27.     this->column = column;
  28.   }
  29.  
  30.   friend std::ostream &operator<<(std::ostream &os, Matrix &m) {
  31.     for (int r = 0; r < m.row; r++) {
  32.       for (int c = 0; c < m.column; c++) {
  33.         os << *(m.content.get() + r * m.column + c) << " ";
  34.       }
  35.       if (r < m.row - 1) os << std::endl;
  36.     }
  37.     return os;
  38.   }
  39.  
  40.   friend Matrix operator*(Matrix &a, Matrix &b) {
  41.     Matrix m;
  42.     if (a.column != b.row)
  43.       return m;
  44.     m.row = a.row;
  45.     m.column = b.column;
  46.     double *array_content = new double[m.row * m.column];
  47.     for (int r = 0; r < m.row; r++) {
  48.       for (int c = 0; c < m.column; c++) {
  49.         double s = 0.0;
  50.         for (int k = 0; k < a.column; k++)
  51.           s += (*(a.content.get() + r * a.column + k) * *(b.content.get() + k * b.column + c));
  52.         *(array_content + r * m.column + c) = s;
  53.       }
  54.     }
  55.     m.content.reset(array_content);
  56.     return m;
  57.   }
  58.  
  59.  
  60.   ~Matrix() {}
  61. };
  62.  
  63. int main() {
  64.   Matrix a, b, m;
  65.   a.set(2, 2,  1.0, -2.0, 2.0,  3.0);
  66.   b.set(2, 2, -2.0,  1.0, 3.0, -1.0);
  67.  
  68.   std::cout << a << std::endl;
  69.   std::cout << "-------------------------" << std::endl;
  70.   std::cout << b << std::endl;
  71.   std::cout << "-------------------------" << std::endl;
  72.  
  73.   m = a * b;
  74.  
  75.   std::cout << m << std::endl;
  76.   std::cout << "-------------------------" << std::endl;
  77.  
  78.   m = b * a;
  79.  
  80.   std::cout << m << std::endl;
  81.   std::cout << "-------------------------" << std::endl;
  82.  
  83.   return 0;
  84. }
  85. /* end */
  86.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
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Standard input is empty
stdout
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1 -2 
2 3 
-------------------------
-2 1 
3 -1 
-------------------------
-8 3 
5 -1 
-------------------------
0 7 
1 -9 
-------------------------
https://ideone.com/umJbre
language:
C++14 (gcc 8.3)
created:
1 year ago
visibility:
secret

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