std:: mdspan

std::mdspan is a view into a contiguous sequence of objects that reinterprets it as a multidimensional array.

Each specialization MDS of mdspan models copyable and satisfies:

• std:: is_nothrow_move_constructible_v < MDS > is true ,
• std:: is_nothrow_move_assignable_v < MDS > is true , and
• std:: is_nothrow_swappable_v < MDS > is true .

A specialization of mdspan is a TriviallyCopyable type if its accessor_type , mapping_type and data_handle_type are TriviallyCopyable types.

Template parameters

Member types

Data members

Member functions

Non-member functions

Helper types and templates

Deduction guides

Notes

Example

#include <cstddef>
#include <mdspan>
#include <print>
#include <vector>
 
int main()
{
    std::vector v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
 
    // View data as contiguous memory representing 2 rows of 6 ints each
    auto ms2 = std::mdspan(v.data(), 2, 6);
    // View the same data as a 3D array 2 x 3 x 2
    auto ms3 = std::mdspan(v.data(), 2, 3, 2);
 
    // Write data using 2D view
    for (std::size_t i = 0; i != ms2.extent(0); i++)
        for (std::size_t j = 0; j != ms2.extent(1); j++)
            ms2[i, j] = i * 1000 + j;
 
    // Read back using 3D view
    for (std::size_t i = 0; i != ms3.extent(0); i++)
    {
        std::println("slice @ i = {}", i);
        for (std::size_t j = 0; j != ms3.extent(1); j++)
        {
            for (std::size_t k = 0; k != ms3.extent(2); k++)
                std::print("{} ", ms3[i, j, k]);
            std::println("");
        }
    }
}

slice @ i = 0
0 1
2 3
4 5
slice @ i = 1
1000 1001
1002 1003
1004 1005

See also