std::ranges::views::take, std::ranges::take_view

views::take(e, f) is expression-equivalent to (where T is std::remove_cvref_t <decltype((e))> and D is ranges::range_difference_t <decltype((e))>):

• ((void)f, decay-copy (e)), if T is a ranges::empty_view , except that the evaluations of e and f are indeterminately sequenced;
• U(ranges::begin (e), ranges::begin (e) + std::min <D>(ranges::distance (e), f)), if T is a specialization of std::span , std::basic_string_view , or ranges::subrange that models both random_access_range and sized_range, where U is

• std::span <typename T::element_type>, if T is a specialization of std::span ;
• T, if T is a specialization of std::basic_string_view ;
• ranges::subrange <ranges::iterator_t <T>>, if T is a specialization of ranges::subrange ;

• ranges::iota_view (*ranges::begin (e),
                    *(ranges::begin (e) + std::min <D>(ranges::distance (e), f))), if T is a specialization of ranges::iota_view that models both random_access_range and sized_range;

• otherwise, take_view(e, f).

#include <algorithm>
#include <iostream>
#include <ranges>
 
int main()
{
 namespace views = std::views;
 auto print = [](char x){ std::cout << x; };
 
 for (const char nums[]{'1', '2', '3'};
 int n : views::iota (0, 5))
 {
 std::cout << "take(" << n << "): ";
 // safely takes only upto min(n, nums.size()) elements:
 std::ranges::for_each (nums | views::take(n), print);
 std::cout << '\n';
 }
}

Output:

take(0): 
take(1): 1
take(2): 12
take(3): 123
take(4): 123