std::array:...ray::cbegin(3)

💅 std::array::begin, std::array::cbegin — std::array:...ray::cbegin(3) / C++ Standard Libary 💅

okay bestie, welcome to the manual page for std::array::begin and std::array::cbegin — the littlest iterator-getters that are absolutely doing main character energy in the C++ Standard Libary. Yes, the manual says “Libary.” We’re keeping it. Periodt. 💖

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✨ NAME ✨

std::array::begin, std::array::cbegin — literally the page name, bestie: std::array::begin,std::array::cbegin. The dash repeats it too: std::array::begin,std::array::cbegin. It’s giving “I said what I said.” 💅

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🌸 Synopsis 🌸

          iterator begin() noexcept;              (1) (since C++11)
                                                      (constexpr since C++17)
          const_iterator begin() const noexcept;  (2) (since C++11)
                                                      (constexpr since C++17)
          const_iterator cbegin() const noexcept; (3) (since C++11)
                                                      (constexpr since C++17)

So there are three overloads, numbered (1), (2), and (3), all since C++11, all noexcept, and all constexpr since C++17. Slay. ✨

Returns an iterator to the first element of the array.

If the array is empty, the returned iterator will be equal to end().

There’s also a little visual in the original: range-begin-end.svg. It’s giving “range-begin-end diagram” and we respect it. 🦋

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🎀 Parameters 🎀

(none) — literally no parameters, not a single one, no cap. 🙈

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💜 Return value 💜

Iterator to the first element. That’s the whole vibe. 🫶

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⭐ Complexity ⭐

Constant. Not linear, not quadratic, just constant. Iconic. 👑

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🔥 Example 🔥

       // Run this code

        #include <algorithm>
        #include <array>
        #include <iomanip>
        #include <iostream>

        int main()
        {
            std::cout << std::boolalpha;

            std::array<int, 0> empty;
            std::cout << "1) "
                      << (empty.begin() == empty.end()) << ' '     // true
                      << (empty.cbegin() == empty.cend()) << '\n'; // true
            // *(empty.begin()) = 42; // => undefined behavior at run-time

            std::array<int, 4> numbers{5, 2, 3, 4};
            std::cout << "2) "
                      << (numbers.begin() == numbers.end()) << ' '    // false
                      << (numbers.cbegin() == numbers.cend()) << '\n' // false
                      << "3) "
                      << *(numbers.begin()) << ' '    // 5
                      << *(numbers.cbegin()) << '\n'; // 5

            *numbers.begin() = 1;
            std::cout << "4) " << *(numbers.begin()) << '\n'; // 1
            // *(numbers.cbegin()) = 42; // compile-time error:
                                         // read-only variable is not
       assignable

            // print out all elements
            std::cout << "5) ";
            std::for_each(numbers.cbegin(), numbers.cend(), [](int x)
            {
                std::cout << x << ' ';
            });
            std::cout << '\n';

            constexpr std::array constants{'A', 'B', 'C'};
            static_assert(constants.begin() != constants.end());   // OK
            static_assert(constants.cbegin() != constants.cend()); // OK
            static_assert(*constants.begin() == 'A');              // OK
            static_assert(*constants.cbegin() == 'A');             // OK
            // *constants.begin() = 'Z'; // compile-time error:
                                         // read-only variable is not
       assignable
        }

bestie, those comments are part of the code and they are staying. Especially the “undefined behavior at run-time” and “compile-time error” ones. We do not edit the sacred comments. 💀

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🍓 Output 🍓

        1) true true
        2) false false
        3) 5 5
        4) 1
        5) 1 2 3 4

Ate. No crumbs. 🌈

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👀 See also 👀

• end — returns an iterator to the end
• cend — (public member function)
• begin
• cbegin — returns an iterator to the beginning of a container or array
• (C++11) — (function template)
• (C++14)

That’s the whole see-also situation, and yes, every line is here. iykyk. 🧚

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💖 source/version: http://cppreference.com · date: 2024.06.10 · page: std::array:...ray::cbegin(3) — bye bestie, go slay some iterators! 🫶💅