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std::basic_...ng::max_size(3) C++ Standard Libarystd::basic_...ng::max_size(3) NAME std::basic_string::max_size - std::basic_string::max_size Synopsis size_type max_size() const; (noexcept since C++11) (constexpr since C++20) 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. Parameters (none) Return value Maximum number of characters. Complexity Constant. Example // Run this code #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::deman- gle(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::ba- sic_string_view<CharT,Traits>) http://cppreference.com 2024.06.10 std::basic_...ng::max_size(3)
NAME | Synopsis | Parameters | Return value | Complexity | Example | Possible output: | See also
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