How to create 2d array c++?

Question

I need to create 2d array in c++.

I can\'t do it by int mas= new int[x][y]; or auto mas= new int[x][y]; I need to create an array dynamical

Answer 1

The C++ tool for creating dynamically sized arrays is named std::vector. Vector is however one-dimensional, so to create a matrix a solution is to create a vector of vectors.

std::vector< std::vector > mas(y, std::vector(x));

It's not the most efficient solution because you pay for the ability to have each row of a different size. You you don't want to pay for this "feature" you have to write your own bidimensional matrix object. For example...

template
struct Matrix
{
    int rows, cols;
    std::vector data;

    Matrix(int rows, int cols)
      : rows(rows), cols(cols), data(rows*cols)
    { }

    T& operator()(int row, int col)
    {
        return data[row*cols + col];
    }

    T operator()(int row, int col) const
    {
        return data[row*cols + col];
    }
};

Then you can use it with

 Matrix mat(y, x);
 for (int i=0; i