matrix.cpp

//matrix_multiplication
int main()
{
  
  int a, b, c, d;
  
//  Entering the matrices dimensions
  do
  {
    cout << "M1 dimensions: ";
    cin >> a >> b;
    cout << "M2 dimensions: ";
    cin >> c >> d;
    
    if (b != c)
    {
      cout << endl << "Matrices cannot be multiplicated" << endl;
      cout << "Re-enter values or close program" << endl << endl;
    }
    
  } while (b != c);
  
//  Creating and filling the matrices
  auto** m1 = new int*[a];
  auto** m2 = new int*[c];
  auto** m3 = new int*[a];
  
  for (int i = 0; i < a; i++)
    *(m1+i) = new int[b];
  
  for (int i = 0; i < c; i++)
    *(m2+i) = new int[d];
  
  for (int i = 0; i < a; i++)
    *(m3+i) = new int[d];
  
  cout << endl << "First matrix " << a << " x " << b << ": " << endl;
  for (int i = 0; i < a; i++)
  {
    for (int j = 0; j < b; j++)
      cin >> *(*(m1+i)+j);
  }
  
  cout << endl << "Second matrix " << c << " x " << d << ": " << endl;
  for (int i = 0; i < c; i++)
  {
    for (int j = 0; j < d; j++)
      cin >> *(*(m2+i)+j);
  }
  
  for (int i = 0; i < a; i++)
  {
    for (int j = 0; j < d; j++)
      *(*(m3+i)+j) = 0;
  }
  
//  =============
  for (int i = 0; i < a; i++)
  {
    for (int j = 0; j < d; j++)
    {
      for (int k = 0; k < b; k++)
      {
        m3[i][j] += m1[i][k] * m2[k][j];
      }
    }
  }
  
  cout << endl << "Resulting matrix: " << endl;
  for (int i = 0; i < a; i++)
  {
    for (int j = 0; j < d; j++)
      cout << m3[i][j] << " ";
    cout << endl;
  }
  
//  Freeing the memory
  for (int i = 0; i < a; i++)
    delete [] *(m1+i);
  delete [] m1;
  
  for (int i = 0; i < c; i++)
    delete [] *(m2+i);
  delete [] m2;
  
  for (int i = 0; i < a; i++)
    delete [] *(m3+i);
  delete [] m3;
  
  _getch();
  return 0;
}