std::span::...pan::cbegin(3)

okay bestie, welcome to the C++ Standard Libary manual — yes, “Libary” is literally how it’s spelled in the header, leave it alone 💅. Today’s page is the std::span::...pan::cbegin(3) moment, and it’s all about std::span::begin and std::span::cbegin. iconic behavior only ✨

💖 NAME 💖

std::span::begin,std::span::cbegin — literally std::span::begin,std::span::cbegin, no cap.

✨ Synopsis ✨

constexpr iterator begin() const noexcept;        (1) (since C++20)
constexpr const_iterator cbegin() const noexcept; (2) (since C++23)

These two cuties return an iterator to the first element of the span.

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

Also: range-begin-end.svg — that’s the little diagram from the original, imagine it right here bestie 🖼️.

🫶 Parameters 🫶

(none) — literally no parameters, not a single one, zero, zilch, nada. slay.

🎀 Return value 🎀

An iterator to the first element. That’s the whole vibe. periodt ✨

🦋 Complexity 🦋

Constant. Always constant. No secret extra loops, bestie. fr fr.

🌸 Example 🌸

// Run this code

#include <iostream>
#include <span>

void print(std::span<const int> array)
{
    std::cout << "array = ";
    for (auto it = array.begin(); it != array.end(); ++it)
        std::cout << *it << ' ';
    std::cout << '\n';
}

void set_first_element(std::span<int> sp, int new_value)
{
    if (!sp.empty())
    {
        std::cout << "old *begin = " << *sp.begin() << '\n';
        *sp.begin() = new_value;
        std::cout << "new *begin = " << *sp.begin() << '\n';
    }
}

int main()
{
    int array[]{1, 3, 4, 5};
    print(array);
    set_first_element(array, 2);
    print(array);
}

Output:

array = 1 3 4 5
old *begin = 1
new *begin = 2
array = 2 3 4 5

👑 See also 👑

• end — returns an iterator to the end
• cend — (public member function) (C++23)
• begin
• cbegin — returns an iterator to the beginning of a container or array (C++11) (function template) (C++14)

sending you kisses from http://cppreference.com 💋, dated 2024.06.10, on the std::span::...pan::cbegin(3) page — bye bestie! 🫶