std::vector and contiguous memory of multidimensional arrays

Question

I know that the standard does not force std::vector to allocate contiguous memory blocks, but all implementations obey this nevertheless.

Suppo

Answer 1

A simple class to create, as you call it, a 2D array, would be something like:

template  2DArray {
private:
    T *m_data;
    int m_stride;
public:
    2DArray(int dimY, int dimX) : m_stride(dimX) : m_data(new[] T[dimX * dimY]) {}
    ~2DArray() { delete[] m_data; }
    T* operator[](int row) { return m_data + m_stride * row; }
}

It's possible to use this like:

2DArray myArray(30,20);

for (int i = 0; i < 30; i++)
    for (int j = 0; j < 20; j++)
        myArray[i][j] = i + j;

Or even pass &myArray[0][0] as address to low-level functions that take some sort of "flat buffers".

But as you see, it turns naive expectations around in that it's myarray[y][x].

Generically, if you interface with code that requires some sort of classical C-style flat array, then why not just use that ?

Edit: As said, the above is simple. No bounds check attempts whatsoever. Just like, "an array".