Question

I created a matrix class:

template <typename T>
class Matrix
{
    static_assert(std::is_arithmetic<T>::value,"");

public:
    Matrix(size_t n_rows, size_t n_cols);
    Matrix(size_t n_rows, size_t n_cols, const T& value);

    void fill(const T& value);
    size_t n_rows() const;
    size_t n_cols() const;

    void print(std::ostream& out) const;

    T& operator()(size_t row_index, size_t col_index);
    T operator()(size_t row_index, size_t col_index) const;
    bool operator==(const Matrix<T>& matrix) const;
    bool operator!=(const Matrix<T>& matrix) const;
    Matrix<T>& operator+=(const Matrix<T>& matrix);
    Matrix<T>& operator-=(const Matrix<T>& matrix);
    Matrix<T> operator+(const Matrix<T>& matrix) const;
    Matrix<T> operator-(const Matrix<T>& matrix) const;
    Matrix<T>& operator*=(const T& value);
    Matrix<T>& operator*=(const Matrix<T>& matrix);
    Matrix<T> operator*(const Matrix<T>& matrix) const;

private:
    size_t rows;
    size_t cols;
    std::vector<T> data;
};

I want to provide a ctor taking an std:initializer_list. I have to ask also the number of rows and columns. I can check if the std:initializer_list size is equal to rows*columns and lunch an exception if is not, but I don’t like very much this solution. If the std:initializer_list is too long, I prefer to use std:initializer_list elements while the matrix is full: the problem is that I don’t now how access the std:initializer_list element by element. Can someone help me? Do you have a better solution to initialize the matrix with std:initializer_list?

Answer 1

You can get at the elements of an initializer_list<T> with the member functions begin() and end(). In this respect, it acts like a container.