std::counte...erator::base(3)

💖 NAME 💖

std::counted_iterator::base - std::counted_iterator::base 🫶

okay so this is the std::counted_iterator::base(3) page, and the manual name folded in near the top is C++ Standard Libary (spelled exactly like that in the header, no cap, we love a typo moment 💅).

🌸 Synopsis 🌸

constexpr const I& base() const& noexcept; (1) (since C++20)
constexpr I base() &&;                     (2) (since C++20)

Returns the underlying base iterator. That's the whole vibe 🦋

1. Returns a reference to the underlying iterator.
2. Move constructs the return value from the underlying iterator.

✨ Parameters ✨

none. zero. not a single parameter, bestie — (none) 🫶

🎀 Return value 🎀

1. A reference to the underlying iterator.
2. An iterator move constructed from the underlying iterator.

🔥 Exceptions 🔥

May throw implementation-defined exceptions. so like, it may throw, and the implementation gets to define them — noted 👑

🌈 Example 🌈

// Run this code

#include <algorithm>
#include <iostream>
#include <iterator>
#include <type_traits>
#include <vector>

int main()
{
    std::vector<int> v{0, 1, 2, 3, 4};

    std::reverse_iterator<std::vector<int>::iterator>
       reverse{v.rbegin()};

    std::counted_iterator counted{reverse, 3};

    static_assert(std::is_same<
        decltype(counted.base()),
        std::reverse_iterator<std::vector<int>::iterator> const&
    >{});

    std::cout << "Print with reverse_iterator: ";
    for (auto r = counted.base(); r != v.rend(); ++r)
        std::cout << *r << ' ';
    std::cout << '\n';

    std::cout << "Print with counted_iterator: ";
    for (; counted != std::default_sentinel; ++counted)
        std::cout << counted[0] << ' ';
    std::cout << '\n';
}

📺 Output: 📺

Print with reverse_iterator: 4 3 2 1 0
Print with counted_iterator: 4 3 2

🧚 Defect reports 🧚

The following behavior-changing defect reports were applied retroactively to previously published C++ standards. periodt.

• DR: LWG 3391 · Applied to: C++20 · Behavior as published: the const version of base returns a copy of the underlying iterator · Correct behavior: returns a reference
• DR: LWG 3593 · Applied to: C++20 · Behavior as published: the const version of base returns a reference but might not be noexcept · Correct behavior: made noexcept

👑 See also 👑

• operator* — accesses the pointed-to element
• operator-> — (public member function) (C++20)
• count — returns the distance to the end (C++20) (public member function)

sign-off cuteness: source is http://cppreference.com, date is 2024.06.10, and the footer page is std::counte...erator::base(3) — mwah 💋✨