std::mdspan - cppreference.com (original) (raw)

std::mdspan is a multidimensional array view that maps a multidimensional index to an element of the array. The mapping and element access policies are configurable, and the underlying array need not be contiguous or even exist in memory at all.

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.

Contents

• 1 Template parameters
• 2 Member types
• 3 Data members
• 4 Member functions
  • 4.1 Element access
  • 4.2 Observers
• 5 Non-member functions
  • 5.1 Subviews
• 6 Helper types and templates
  • 6.1 Layout mapping policies
  • 6.2 Subviews helpers
• 7 Deduction guides
• 8 Notes
• 9 Example
• 10 See also

[edit] Template parameters

[edit] Member types

[edit] Data members

[edit] Member functions

[edit] Non-member functions

[edit] Helper types and templates

[edit] Deduction guides

[edit] Notes

[edit] Example

Can be previewed on Compiler Explorer.

#include #include #include #include   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(""); } } }

Output:

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

[edit] See also

| | a non-owning view over a contiguous sequence of objects (class template) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | numeric arrays, array masks and array slices (class template) [edit] |