std::full_e...ull_extent_t(3)

okay so 💖 this is the std::full_e...ull_extent_t(3) page from the C++ Standard Libary manual, and it's literally about the slice-specifier duo std::full_extent and std::full_extent_t. bestie, they're the “gimme the whole range” besties for std::submdspan, no cap. 🫶

💖 NAME 💖

std::full_extent,std::full_extent_t — std::full_extent,std::full_extent_t

yes bestie, the name is exactly that, comma and all. iconic. 💅

✨ Synopsis ✨

Defined in header <mdspan>:

struct full_extent_t { explicit full_extent_t() = default; }; (1)

(since C++26)

inline constexpr std::full_extent_t full_extent {};           (2)

(since C++26)

okay so 1) the class std::full_extent_t is a slice specifier type that can be used in std::submdspan.

and 2) the corresponding std::full_extent instance of (1) is a slice specifier to indicate full range of indices in the specified extent in std::submdspan. periodt. ✨

since C++26, bestie — this is the new-new era, so keep that in mind. 🦋

🌸 Example 🌸

// Run this code

        #include <mdspan>
        #include <print>

        void print_view(auto view)
        {
            static_assert(view.rank() <= 2);

            if constexpr (view.rank() == 2)
            {
              for (std::size_t i = 0; i < view.extent(0); ++i)
              {
                for (std::size_t j = 0; j < view.extent(1); ++j)
                  std::print("{} ", view[i, j]);
                std::println("");
              }
            }
            else if constexpr (view.rank() == 1)
            {
              for (std::size_t i = 0; i < view.extent(0); ++i)
                std::print("{} ", view[i]);
              std::println("");
            }
            else
            {
              std::println("{}", view[]);
            }
            std::println("");
        }

        int main()
        {
            char letters [] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I' };
            std::mdspan view (letters, 3, 3);

            print_view(view);
            print_view(std::submdspan(view, std::full_extent,
       std::full_extent));
            print_view(std::submdspan(view, std::full_extent, 1));
            print_view(std::submdspan(view, 1, std::full_extent));
            print_view(std::submdspan(view, 2, 1));
        }

🎀 Possible output 🎀

        A B C
        D E F
        G H I

        A B C
        D E F
        G H I

        B E H

        D E F

        H

🦋 See also 🦋

• submdspan — returns a view of a subset of an existing mdspan (C++26) (function template)

made with 💖 by the http://cppreference.com girlies, version/date 2024.06.10, and the page is std::full_e...ull_extent_t(3). periodt. 🎀