std::basic_...ng::max_size(3)

🌸 NAME 🌸

std::basic_string::max_size — literally std::basic_string::max_size, bestie. It's giving self-titled main character energy ✨. This page is from the C++ Standard Libary manual (yes, "Libary" with the typo in the header, I'm just reporting the vibes 😭), and the header folds it in as std::basic_...ng::max_size(3) because truncation ate the middle of the word and left us with a mystery 💀.

🦋 Synopsis 🦋

Here's the signature, no cap:

size_type max_size() const;  (noexcept since C++11)
                             (constexpr since C++20)

It returns the maximum number of elements the string is able to hold due to system or library implementation limitations, i.e. std::distance(begin(), end()) for the largest string. That's the whole assignment, periodt.

✨ Parameters ✨

(none) — no parameters. Zero. Zilch. Nada. 🫶

💖 Return value 💖

Maximum number of characters. That's it. That's the tea. 🍓

🔥 Complexity 🔥

Constant. Literally constant. No cap.

🎀 Example 🎀

The original page has a literal // Run this code note above the block, and then this exact example code (yes, the line wraps are chaotic — I did not come here to fix cppreference's formatting, I came to serve facts 💅):

        #include <array>
        #include <climits>
        #include <iomanip>
        #include <iostream>
        #include <locale>
        #include <string>
        #include <typeinfo>

        #include <boost/core/demangle.hpp>

        template<typename T>
        void print_basic_string_max_size()
        {
            std::basic_string<T> s;
            auto max_size = s.max_size();
            std::cout.imbue(std::locale("en_US.UTF-8"));
            std::cout << "basic_string<" <<
       boost::core::demangle(typeid(T).name())
                      << ">:\n\t" << max_size << " = ";
            std::cout << std::setprecision(3) << (double) max_size << " = ";
            std::cout.imbue(std::locale("C"));
            std::cout << std::hex << std::setfill('0') << "0x"
                      << std::setw(sizeof(typename decltype(s)::size_type) <<
       1)
                      << max_size << '\n' << std::dec;
        };

        int main()
        {
            std::cout << "Pointer size: " << CHAR_BIT * sizeof(void*) << "
       bits\n"
                         "Maximum sizes:\n";

            print_basic_string_max_size<char>();
            print_basic_string_max_size<char16_t>();
            print_basic_string_max_size<char32_t>();
            print_basic_string_max_size<wchar_t>();
            print_basic_string_max_size<long>();

            using CharT = std::array<char, 01232>;
            print_basic_string_max_size<CharT>();
        }

Possible output:

        Pointer size: 64 bits
        Maximum sizes:
        basic_string<char>:
                9,223,372,036,854,775,807 = 9.22e+18 = 0x7fffffffffffffff
        basic_string<char16_t>:
                4,611,686,018,427,387,903 = 4.61e+18 = 0x3fffffffffffffff
        basic_string<char32_t>:
                2,305,843,009,213,693,951 = 2.31e+18 = 0x1fffffffffffffff
        basic_string<wchar_t>:
                2,305,843,009,213,693,951 = 2.31e+18 = 0x1fffffffffffffff
        basic_string<long>:
                1,152,921,504,606,846,975 = 1.15e+18 = 0x0fffffffffffffff
        basic_string<std::array<char, 666ul>>:
                13,848,906,962,244,407 = 1.38e+16 = 0x00313381ec031337

🌈 See also 🌈

• size — returns the number of characters
• length — (public member function)
• max_size — returns the maximum number of characters (public member function of std::basic_string_view<CharT,Traits>)

xoxo, your Unix bestie 💅 — source/version/date: http://cppreference.com, 2024.06.10, page std::basic_...ng::max_size(3). periodt. 🌟