Matrix class with std::array

Question

I want to build a simple matrix class. The relevant part of my header file looks like this:

template <typename T>
class matrix
{
private:
  unsigned int nrows;
  unsigned int ncols;
  std::array<std::array<T, ncols>, nrows> mat;

public:
  matrix();

  unsigned int getCols() const;
  unsigned int getRows() const;

};

The problem here is that the two-dimensional array (called mat) needs the number of rows and columns. Obviously, this doesn't work but I don't know how to solve this issue.

My source file:

template <typename T>
matrix<T>::matrix() : nrows(0), ncols(0) {}

template <typename T>
unsigned int matrix<T>::getCols() const {
  return ncols;
}

template <typename T>
unsigned int matrix<T>::getRows() const {
  return nrows;
}

The initialization of a matrix should look something like this:

matrix<double> my_matrix;

Use std::vector<std::vector> std::array<std::array> dimensions must be known at compile time. — Dimitrios Bouzas
– Dimitrios Bouzas, Commented May 9, 2015 at 9:14

Ajay · Accepted Answer · 2015-05-09 09:17:40Z

1

You cant have variable size argument for size of array. Therefore you must have two more template arguments for matrix class.

template <typename T, size_t ROWS, size_t COLS>
class matrix
...

answered May 9, 2015 at 9:17

Ajay

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1 Comment

beginneR Over a year ago

Thank you for the hint, I've implemented the class with std::vector now due to the need to push_back etc.

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