C++: What is std::ranges::iota (C++23)?

1#include <ranges>
2
3std::vector<int> v(5);
4
5// Fill with 0, 1, 2, 3, 4
6std::ranges::iota(v, 0);
7// v = {0, 1, 2, 3, 4}
8
9// Start from any value
10std::ranges::iota(v, 10);
11// v = {10, 11, 12, 13, 14}
12
13// Works with any output range
14std::array<int, 5> arr;
15std::ranges::iota(arr, 100);
16// arr = {100, 101, 102, 103, 104}
17
18// With custom type
19std::vector<char> chars(5);
20std::ranges::iota(chars, 'A');
21// chars = {'A', 'B', 'C', 'D', 'E'}
22
23// Combine with views
24std::vector<int> result(10);
25std::ranges::iota(result, 1);
26auto squares = result
27    | std::views::transform([](int x) { return x * x; });
28// 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
29
30// Compile-time
31std::array<int, 5> arr2;
32constexpr auto iota_arr = [] {
33    std::array<int, 5> a;
34    std::ranges::iota(a, 1);
35    return a;
36}();
37// iota_arr = {1, 2, 3, 4, 5}