The header <string> defines the basic_string class template for manipulating varying-length sequences of char-like objects and four typedefs, string, u16string, u32string, and wstring, that name the specializations basic_string<char>, basic_string<char16_t>, basic_string<char32_t>, and basic_string<wchar_t>, respectively.
Header <string> synopsis
#include <initializer_list> namespace std { // [char.traits], character traits: template<class charT> struct char_traits; template <> struct char_traits<char>; template <> struct char_traits<char16_t>; template <> struct char_traits<char32_t>; template <> struct char_traits<wchar_t>; // [basic.string], basic_string: template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> > class basic_string; template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(basic_string<charT,traits,Allocator>&& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(const basic_string<charT,traits,Allocator>& lhs, basic_string<charT,traits,Allocator>&& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(basic_string<charT,traits,Allocator>&& lhs, basic_string<charT,traits,Allocator>&& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(const charT* lhs, basic_string<charT,traits,Allocator>&& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(charT lhs, basic_string<charT,traits,Allocator>&& rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(basic_string<charT,traits,Allocator>&& lhs, const charT* rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(const basic_string<charT,traits,Allocator>& lhs, charT rhs); template<class charT, class traits, class Allocator> basic_string<charT,traits,Allocator> operator+(basic_string<charT,traits,Allocator>&& lhs, charT rhs); template<class charT, class traits, class Allocator> bool operator==(const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator==(const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> bool operator!=(const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator!=(const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator!=(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> bool operator< (const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator< (const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> bool operator< (const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator> (const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator> (const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> bool operator> (const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator<=(const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator<=(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> bool operator<=(const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator>=(const basic_string<charT,traits,Allocator>& lhs, const basic_string<charT,traits,Allocator>& rhs); template<class charT, class traits, class Allocator> bool operator>=(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs); template<class charT, class traits, class Allocator> bool operator>=(const charT* lhs, const basic_string<charT,traits,Allocator>& rhs); // [string.special], swap: template<class charT, class traits, class Allocator> void swap(basic_string<charT,traits,Allocator>& lhs, basic_string<charT,traits,Allocator>& rhs); // [string.io], inserters and extractors: template<class charT, class traits, class Allocator> basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>& is, basic_string<charT,traits,Allocator>& str); template<class charT, class traits, class Allocator> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const basic_string<charT,traits,Allocator>& str); template<class charT, class traits, class Allocator> basic_istream<charT,traits>& getline(basic_istream<charT,traits>& is, basic_string<charT,traits,Allocator>& str, charT delim); template<class charT, class traits, class Allocator> basic_istream<charT,traits>& getline(basic_istream<charT,traits>&& is, basic_string<charT,traits,Allocator>& str, charT delim); template<class charT, class traits, class Allocator> basic_istream<charT,traits>& getline(basic_istream<charT,traits>& is, basic_string<charT,traits,Allocator>& str); template<class charT, class traits, class Allocator> basic_istream<charT,traits>& getline(basic_istream<charT,traits>&& is, basic_string<charT,traits,Allocator>& str); // basic_string typedef names typedef basic_string<char> string; typedef basic_string<char16_t> u16string; typedef basic_string<char32_t> u32string; typedef basic_string<wchar_t> wstring; // [string.conversions], numeric conversions: int stoi(const string& str, size_t *idx = 0, int base = 10); long stol(const string& str, size_t *idx = 0, int base = 10); unsigned long stoul(const string& str, size_t *idx = 0, int base = 10); long long stoll(const string& str, size_t *idx = 0, int base = 10); unsigned long long stoull(const string& str, size_t *idx = 0, int base = 10); float stof(const string& str, size_t *idx = 0); double stod(const string& str, size_t *idx = 0); long double stold(const string& str, size_t *idx = 0); string to_string(int val); string to_string(unsigned val); string to_string(long val); string to_string(unsigned long val); string to_string(long long val); string to_string(unsigned long long val); string to_string(float val); string to_string(double val); string to_string(long double val); int stoi(const wstring& str, size_t *idx = 0, int base = 10); long stol(const wstring& str, size_t *idx = 0, int base = 10); unsigned long stoul(const wstring& str, size_t *idx = 0, int base = 10); long long stoll(const wstring& str, size_t *idx = 0, int base = 10); unsigned long long stoull(const wstring& str, size_t *idx = 0, int base = 10); float stof(const wstring& str, size_t *idx = 0); double stod(const wstring& str, size_t *idx = 0); long double stold(const wstring& str, size_t *idx = 0); wstring to_wstring(int val); wstring to_wstring(unsigned val); wstring to_wstring(long val); wstring to_wstring(unsigned long val); wstring to_wstring(long long val); wstring to_wstring(unsigned long long val); wstring to_wstring(float val); wstring to_wstring(double val); wstring to_wstring(long double val); // [basic.string.hash], hash support: template <class T> struct hash; template <> struct hash<string>; template <> struct hash<u16string>; template <> struct hash<u32string>; template <> struct hash<wstring>; }