C++: What is std::span?

1#include <span>
2
3void process(std::span<int> data) {
4    for (int& x : data) {
5        x *= 2;
6    }
7}
8
9int arr[] = {1, 2, 3};
10process(arr);           // works with C array
11process(std::vector<int>{4, 5, 6}); // works with vector
12process({&arr[0], 2});  // subspan

1auto sub = data.subspan(1, 3); // elements [1, 4)
2auto first = data.first(5);     // first 5 elements
3auto last = data.last(5);       // last 5 elements