std::ranges...on_view::end(3)

💅 std::ranges...on_view::end(3) 💅

okay so bestie, this is the C++ Standard Libary page for std::ranges...on_view::end(3) — the NAME line goes std::ranges::common_view::end, and no cap, this is the end member of std::ranges::common_view. Let’s get into it 🫶

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🌸 NAME 🌸

std::ranges::common_view::end — std::ranges::common_view::end (yes, it says it twice; we love a consistent icon 💖)

✨ Synopsis ✨

Two overloads, both since C++20, living their best lives:

constexpr auto end() requires (!__simple_view<V>);          (1)
(since C++20)
constexpr auto end() const requires ranges::range<const V>; (2)
(since C++20)

So like, what are they actually doing?

1. Returns an iterator representing the end of the common_view, that is:
   • ranges::begin(base_) + ranges::size(base_), if both ranges::random_access_range<V> and ranges::sized_range<V> are satisfied,
   • std::common_iterator<ranges::iterator_t<V>, ranges::sentinel_t<V>>(ranges::end(base_)) otherwise.

Here base_ (the name is for exposition purposes only) is the underlying view.

2. Same as (1), but V is const-qualified.

💖 Parameters 💖

(none) — zero, zip, nada 🌸

🦋 Return value 🦋

An iterator representing the end of the underlying view. That’s the whole vibe 💅

🍓 Example 🍓

Run this code, bestie:

// Run this code

#include <iostream>
#include <numeric>
#include <ranges>

int main()
{
    constexpr int n{4};

    constexpr auto v1 = std::views::iota(1)
                      | std::views::take(n)
                      | std::views::common
                      ;
    constexpr auto v2 = std::views::iota(2)
                      | std::views::take(n)
                      ;
    const int product = std::inner_product(v1.begin(), v1.end(),
                                           v2.begin(),
                                           0);
    std::cout << product << '\n';
}

🌈 Output 🌈

It prints:

40

💀 Defect reports 💀

The manual says: “The following behavior-changing defect reports were applied retroactively to previously published C++ standards.”

• LWG 4012 — applied to C++20; behavior as published: non-const overload missed simple-view check; correct behavior: added.

👑 See also 👑

• begin (C++20) — returns an iterator to the beginning; public member function.
• ranges::begin (C++20) — returns an iterator to the beginning of a range; customization point object.
• ranges::end (C++20) — returns a sentinel indicating the end of a range; customization point object.

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source/version: http://cppreference.com · date: 2024.06.10 · page: std::ranges...on_view::end(3) — bye bestie, go crush those ranges 💜✨