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

1#include <ranges>
2
3// Repeat value 5 times
4auto v = std::views::repeat(42, 5);
5for (int x : v) {
6    std::cout << x << " ";  // 42 42 42 42 42
7}
8
9// Infinite repeat (use with take)
10auto infinite = std::views::repeat(0);
11auto first5 = infinite | std::views::take(5);
12for (int x : first5) {
13    std::cout << x << " ";  // 0 0 0 0 0
14}
15
16// Repeat with transform
17auto pattern = std::views::repeat(std::string("ab"), 3)
18    | std::views::join;
19// "ababab"
20
21// Useful for padding
22std::vector<int> data = {1, 2, 3};
23auto padded = data
24    | std::views::chain(std::views::repeat(0, 5 - data.size()));
25// 1 2 3 0 0
26
27// Compile-time
28constexpr auto zeros = std::views::repeat(0, 10);
29static_assert(zeros.size() == 10);
30
31// Size
32std::cout << v.size();  // 5
33std::cout << v[2];     // 42
34
35// Random access
36auto it = v.begin();
37std::cout << *(it + 3);  // 42