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std::full_extent, std::full_extent_t

From cppreference.com
< cpp‎ | container‎ | mdspan
 
 
 
 
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)
1) The class std::full_extent_t is a slice specifier type that can be used in std::submdspan.
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.

[edit] Example

#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

[edit] See also

(C++26)
returns a view of a subset of an existing mdspan
(function template) [edit]