std::full_extent, std::full_extent_t

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< cpp‎ | container‎ | mdspan
 
C++
 
Containers library
 
std::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.

Example

Run this code
#include <mdspan>
#include <print>
 
void print(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()
{
    const char letters []{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I'};
    const std::mdspan view(letters, 3, 3);
 
    print(view);
    print(std::submdspan(view, std::full_extent, std::full_extent));
    print(std::submdspan(view, std::full_extent, 1));
    print(std::submdspan(view, 1, std::full_extent));
    print(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

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