mdspan/mdspanstride.cpp

The following code example is taken from the book
C++23 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2026
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <vector>
#include <ranges>
#include <mdspan>
#include "print2d.hpp"

int main()
{
  std::vector vec{std::from_range, std::views::iota(1, 81)};  // elements from 1 to 80

  // 4 rows of 3 columns over every second element:
  std::mdspan mds{vec.data(),
                  std::layout_stride::mapping{std::extents{4, 3},
                                              std::array{6, 2}}};
  print2D(mds);

  // maximum rows for 3 columns over every second element:
  std::layout_stride::mapping map2nd3{std::extents{(vec.size()+1) / 6, 3},
                                      std::array{6, 2}};
  std::println("required size: {}", map2nd3.required_span_size());
  mds = std::mdspan{vec.data(), map2nd3};
  print2D(mds);
}