#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>();}

Pointer size: 64 bitsMaximum sizes:basic_string<char>:        9,223,372,036,854,775,807 = 9.22e+18 = 0x7fffffffffffffffbasic_string<char16_t>:        4,611,686,018,427,387,903 = 4.61e+18 = 0x3fffffffffffffffbasic_string<char32_t>:        2,305,843,009,213,693,951 = 2.31e+18 = 0x1fffffffffffffffbasic_string<wchar_t>:        2,305,843,009,213,693,951 = 2.31e+18 = 0x1fffffffffffffffbasic_string<long>:        1,152,921,504,606,846,975 = 1.15e+18 = 0x0fffffffffffffffbasic_string<std::array<char, 666ul>>:        13,848,906,962,244,407 = 1.38e+16 = 0x00313381ec031337