31 Input/output library [input.output]

31.8 String-based streams [string.streams]

31.8.5 Class template basic_stringstream [stringstream]

31.8.5.1 General [stringstream.general]

namespace std { template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>> class basic_stringstream : public basic_iostream<charT, traits> { public: using char_type = charT; using int_type = typename traits::int_type; using pos_type = typename traits::pos_type; using off_type = typename traits::off_type; using traits_type = traits; using allocator_type = Allocator; // [stringstream.cons], constructors basic_stringstream() : basic_stringstream(ios_base::out | ios_base::in) {} explicit basic_stringstream(ios_base::openmode which); explicit basic_stringstream( const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::out | ios_base::in); basic_stringstream(ios_base::openmode which, const Allocator& a); explicit basic_stringstream( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::out | ios_base::in); template<class SAlloc> basic_stringstream( const basic_string<charT, traits, SAlloc>& s, const Allocator& a) : basic_stringstream(s, ios_base::out | ios_base::in, a) {} template<class SAlloc> basic_stringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a); template<class SAlloc> explicit basic_stringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::out | ios_base::in); template<class T> explicit basic_stringstream(const T& t, ios_base::openmode which = ios_base::out | ios_base::in); template<class T> basic_stringstream(const T& t, const Allocator& a); template<class T> basic_stringstream(const T& t, ios_base::openmode which, const Allocator& a); basic_stringstream(const basic_stringstream&) = delete; basic_stringstream(basic_stringstream&& rhs); basic_stringstream& operator=(const basic_stringstream&) = delete; basic_stringstream& operator=(basic_stringstream&& rhs); // [stringstream.swap], swap void swap(basic_stringstream& rhs); // [stringstream.members], members basic_stringbuf<charT, traits, Allocator>* rdbuf() const; basic_string<charT, traits, Allocator> str() const &; template<class SAlloc> basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const; basic_string<charT, traits, Allocator> str() &&; basic_string_view<charT, traits> view() const noexcept; void str(const basic_string<charT, traits, Allocator>& s); template<class SAlloc> void str(const basic_string<charT, traits, SAlloc>& s); void str(basic_string<charT, traits, Allocator>&& s); template<class T> void str(const T& t); private: basic_stringbuf<charT, traits, Allocator> sb; // exposition only }; }
The class template basic_stringstream<charT, traits> supports reading and writing from objects of class basic_string<charT, traits, Allocator>.
It uses a basic_stringbuf<charT, traits, Allocator> object to control the associated sequence.
For the sake of exposition, the maintained data is presented here as
  • sb, the stringbuf object.

31.8.5.2 Constructors [stringstream.cons]

explicit basic_stringstream(ios_base::openmode which);
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_stringbuf<charT, traits, Allocator>(which).
explicit basic_stringstream( const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::out | ios_base::in);
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_stringbuf<charT, traits, Allocator>(s, which).
basic_stringstream(ios_base::openmode which, const Allocator& a);
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_stringbuf<charT, traits, Allocator>(which, a) ([stringbuf.cons]).
explicit basic_stringstream( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::out | ios_base::in);
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_stringbuf<charT, traits, Allocator>(std​::​move(s), which) ([stringbuf.cons]).
template<class SAlloc> basic_stringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a);
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_stringbuf<charT, traits, Allocator>(s, which, a) ([stringbuf.cons]).
template<class SAlloc> explicit basic_stringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::out | ios_base::in);
Constraints: is_same_v<SAlloc,Allocator> is false.
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_stringbuf<charT, traits, Allocator>(s, which) ([stringbuf.cons]).
template<class T> explicit basic_stringstream(const T& t, ios_base::openmode which = ios_base::out | ios_base::in); template<class T> basic_stringstream(const T& t, const Allocator& a); template<class T> basic_stringstream(const T& t, ios_base::openmode which, const Allocator& a);
Let which be ios_base​::​out | ios_base​::​in for the overload with no parameter which, and a be Allocator() for the overload with no parameter a.
Constraints: is_convertible_v<const T&, basic_string_view<charT, traits>> is true.
Effects: Initializes the base class with addressof(sb), and direct-non-list-initializes sb with t, which, a.
basic_stringstream(basic_stringstream&& rhs);
Effects: Move constructs from the rvalue rhs.
This is accomplished by move constructing the base class, and the contained basic_stringbuf.
Then calls basic_istream<charT, traits>​::​set_rdbuf(addressof(sb)) to install the contained basic_stringbuf.

31.8.5.3 Swap [stringstream.swap]

void swap(basic_stringstream& rhs);
Effects: Equivalent to: basic_iostream<charT,traits>::swap(rhs); sb.swap(rhs.sb);
template<class charT, class traits, class Allocator> void swap(basic_stringstream<charT, traits, Allocator>& x, basic_stringstream<charT, traits, Allocator>& y);
Effects: Equivalent to x.swap(y).

31.8.5.4 Member functions [stringstream.members]

basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
Returns: const_cast<basic_stringbuf<charT, traits, Allocator>*>(addressof(sb)).
basic_string<charT, traits, Allocator> str() const &;
Effects: Equivalent to: return rdbuf()->str();
template<class SAlloc> basic_string<charT,traits,SAlloc> str(const SAlloc& sa) const;
Effects: Equivalent to: return rdbuf()->str(sa);
basic_string<charT,traits,Allocator> str() &&;
Effects: Equivalent to: return std​::​move(*rdbuf()).str();
basic_string_view<charT, traits> view() const noexcept;
Effects: Equivalent to: return rdbuf()->view();
void str(const basic_string<charT, traits, Allocator>& s);
Effects: Equivalent to: rdbuf()->str(s);
template<class SAlloc> void str(const basic_string<charT, traits, SAlloc>& s);
Effects: Equivalent to: rdbuf()->str(s);
void str(basic_string<charT, traits, Allocator>&& s);
Effects: Equivalent to: rdbuf()->str(std​::​move(s));
template<class T> void str(const T&);
Constraints: is_convertible_v<const T&, basic_string_view<charT, traits>> is true.
Effects: Equivalent to: rdbuf()->str(t);