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

The standard does require the memory of an std::vector to be contiguous. On the other hand, if you write something like:

std::vector > v;

the global memory (all of the v[i][j]) will not be contiguous. The usual way of creating 2D arrays is to use a single

std::vector v;

and calculate the indexes, exactly as you suggest doing with float. (You can also create a second std::vector with the addresses if you want. I've always just recalculated the indexes, however.)