Multidimensional Arrays and std::mdspan

Accessing Elements in an mdspan

How do I access individual elements in a multidimensional span?

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To access individual elements in a multidimensional span (std::mdspan), you can use the [] operator with multiple indices, one for each dimension.

For example, let's say we have a 2D mdspan called matrix with dimensions 3x4. Here's how we can access its elements:

#include <mdspan>
#include <iostream>

int main() {
  std::array<int, 12> arr{
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

  std::mdspan<int, std::extents<
    std::size_t, 3, 4>> matrix{};

  // Accessing elements
  std::cout << "Element at (0, 0): "
    << matrix[0, 0] << "\n";
  std::cout << "Element at (1, 2): "
    << matrix[1, 2] << "\n";
  std::cout << "Element at (2, 3): "
    << matrix[2, 3] << "\n";
Element at (0, 0): 1
Element at (1, 2): 7
Element at (2, 3): 12

The first index represents the row, and the second index represents the column. So, matrix[0, 0] accesses the element at the first row and first column, matrix[1, 2] accesses the element at the second row and third column, and so on.

Remember that the indices start at 0 for each dimension. Also, make sure to provide the correct number of indices matching the rank (number of dimensions) of the mdspan.

Answers to questions are automatically generated and may not have been reviewed.

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