29 Input/output library [input.output]

29.8 String-based streams [string.streams]

29.8.3 Class template basic_­istringstream [istringstream]

29.8.3.1 General [istringstream.general]

namespace std { template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT>> class basic_istringstream : public basic_istream<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; // [istringstream.cons], constructors basic_istringstream() : basic_istringstream(ios_base::in) {} explicit basic_istringstream(ios_base::openmode which); explicit basic_istringstream( const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::in); basic_istringstream(ios_base::openmode which, const Allocator& a); explicit basic_istringstream( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::in); template<class SAlloc> basic_istringstream( const basic_string<charT, traits, SAlloc>& s, const Allocator& a) : basic_istringstream(s, ios_base::in, a) {} template<class SAlloc> basic_istringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a); template<class SAlloc> explicit basic_istringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::in); basic_istringstream(const basic_istringstream&) = delete; basic_istringstream(basic_istringstream&& rhs); // [istringstream.assign], assign and swap basic_istringstream& operator=(const basic_istringstream&) = delete; basic_istringstream& operator=(basic_istringstream&& rhs); void swap(basic_istringstream& rhs); // [istringstream.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); private: basic_stringbuf<charT, traits, Allocator> sb; // exposition only }; }
The class basic_­istringstream<charT, traits, Allocator> supports reading objects of class basic_­string<​charT, traits, Allocator>.
It uses a basic_­stringbuf<charT, traits, Allocator> object to control the associated storage.
For the sake of exposition, the maintained data is presented here as:
  • sb, the stringbuf object.

29.8.3.2 Constructors [istringstream.cons]

explicit basic_istringstream(ios_base::openmode which);
Effects: Initializes the base class with basic_­istream<charT, traits>(addressof(sb)) ([istream]) and sb with basic_­stringbuf<charT, traits, Allocator>(which | ios_­base​::​in) ([stringbuf.cons]).
explicit basic_istringstream( const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::in);
Effects: Initializes the base class with basic_­istream<charT, traits>(addressof(sb)) ([istream]) and sb with basic_­stringbuf<charT, traits, Allocator>(s, which | ios_­base​::​in)
([stringbuf.cons]).
basic_istringstream(ios_base::openmode which, const Allocator& a);
Effects: Initializes the base class with basic_­istream<charT, traits>(addressof(sb)) ([istream]) and sb with basic_­stringbuf<charT, traits, Allocator>(which | ios_­base​::​in, a) ([stringbuf.cons]).
explicit basic_istringstream( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::in);
Effects: Initializes the base class with basic_­istream<charT, traits>(addressof(sb)) ([istream]) and sb with basic_­stringbuf<charT, traits, Allocator>(std​::​move(s), which | ios_­base​::​​in) ([stringbuf.cons]).
template<class SAlloc> basic_istringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a);
Effects: Initializes the base class with basic_­istream<charT, traits>(addressof(sb)) ([istream]) and sb with basic_­stringbuf<charT, traits, Allocator>(s, which | ios_­base​::​in, a)
([stringbuf.cons]).
template<class SAlloc> explicit basic_istringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::in);
Effects: Initializes the base class with basic_­istream<charT, traits>(addressof(sb)) ([istream]) and sb with basic_­stringbuf<charT, traits, Allocator>(s, which | ios_­base​::​in) ([stringbuf.cons]).
basic_istringstream(basic_istringstream&& 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.

29.8.3.3 Assignment and swap [istringstream.assign]

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

29.8.3.4 Member functions [istringstream.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));