13 KiB
[ostringstream]
31 Input/output library [input.output]
31.8 String-based streams [string.streams]
31.8.4 Class template basic_ostringstream [ostringstream]
31.8.4.1 General [ostringstream.general]
namespace std {template<class charT, class traits = char_traits, class Allocator = allocator>class basic_ostringstream : public basic_ostream<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; // [ostringstream.cons], constructors basic_ostringstream() : basic_ostringstream(ios_base::out) {}explicit basic_ostringstream(ios_base::openmode which); explicit basic_ostringstream(const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::out); basic_ostringstream(ios_base::openmode which, const Allocator& a); explicit basic_ostringstream( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::out); template basic_ostringstream(const basic_string<charT, traits, SAlloc>& s, const Allocator& a): basic_ostringstream(s, ios_base::out, a) {}template basic_ostringstream(const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a); templateexplicit basic_ostringstream(const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::out); templateexplicit basic_ostringstream(const T& t, ios_base::openmode which = ios_base::out); template basic_ostringstream(const T& t, const Allocator& a); template basic_ostringstream(const T& t, ios_base::openmode which, const Allocator& a); basic_ostringstream(const basic_ostringstream&) = delete; basic_ostringstream(basic_ostringstream&& rhs);
basic_ostringstream& operator=(const basic_ostringstream&) = delete; basic_ostringstream& operator=(basic_ostringstream&& rhs); // [ostringstream.swap], swapvoid swap(basic_ostringstream& rhs); // [ostringstream.members], members basic_stringbuf<charT, traits, Allocator>* rdbuf() const;
basic_string<charT, traits, Allocator> str() const &; template 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); templatevoid str(const basic_string<charT, traits, SAlloc>& s); void str(basic_string<charT, traits, Allocator>&& s); templatevoid str(const T& t); private: basic_stringbuf<charT, traits, Allocator> sb; // exposition only};}
The classbasic_ostringstream<charT, traits, Allocator> supports writing objects of classbasic_string<charT, traits, Allocator>.
It uses abasic_stringbuf object to control the associated storage.
For the sake of exposition, the maintained data is presented here as:
sb, the stringbuf object.
31.8.4.2 Constructors [ostringstream.cons]
explicit basic_ostringstream(ios_base::openmode which);
Effects: Initializes the base class withbasic_ostream<charT, traits>(addressof(sb)) ([ostream]) and sb withbasic_stringbuf<charT, traits, Allocator>(which | ios_base::out) ([stringbuf.cons]).
explicit basic_ostringstream( const basic_string<charT, traits, Allocator>& s, ios_base::openmode which = ios_base::out);
Effects: Initializes the base class withbasic_ostream<charT, traits>(addressof(sb)) ([ostream])
and sb withbasic_stringbuf<charT, traits, Allocator>(s, which | ios_base::out)
([stringbuf.cons]).
basic_ostringstream(ios_base::openmode which, const Allocator& a);
Effects: Initializes the base class withbasic_ostream<charT, traits>(addressof(sb)) ([ostream])
and sb withbasic_stringbuf<charT, traits, Allocator>(which | ios_base::out, a)
([stringbuf.cons]).
explicit basic_ostringstream( basic_string<charT, traits, Allocator>&& s, ios_base::openmode which = ios_base::out);
Effects: Initializes the base class withbasic_ostream<charT, traits>(addressof(sb)) ([ostream]) and sb withbasic_stringbuf<charT, traits, Allocator>(std::move(s), which | ios_base::out) ([stringbuf.cons]).
template<class SAlloc> basic_ostringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which, const Allocator& a);
Effects: Initializes the base class withbasic_ostream<charT, traits>(addressof(sb)) ([ostream])
and sb withbasic_stringbuf<charT, traits, Allocator>(s, which | ios_base::out, a)
([stringbuf.cons]).
template<class SAlloc> explicit basic_ostringstream( const basic_string<charT, traits, SAlloc>& s, ios_base::openmode which = ios_base::out);
Constraints: is_same_v<SAlloc, Allocator> is false.
Effects: Initializes the base class withbasic_ostream<charT, traits>(addressof(sb)) ([ostream])
and sb withbasic_stringbuf<charT, traits, Allocator>(s, which | ios_base::out)
([stringbuf.cons]).
template<class T> explicit basic_ostringstream(const T& t, ios_base::openmode which = ios_base::out); template<class T> basic_ostringstream(const T& t, const Allocator& a); template<class T> basic_ostringstream(const T& t, ios_base::openmode which, const Allocator& a);
Let which be ios_base::out for the overload with no parameter which, anda 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 | ios_base::out, a.
basic_ostringstream(basic_ostringstream&& rhs);
Effects: Move constructs from the rvalue rhs.
This is accomplished by move constructing the base class, and the containedbasic_stringbuf.
Then calls basic_ostream<charT, traits>::set_rdbuf(addressof(sb)) to install the contained basic_stringbuf.
31.8.4.3 Swap [ostringstream.swap]
void swap(basic_ostringstream& rhs);
Effects: Equivalent to:basic_ostream<charT, traits>::swap(rhs);sb.swap(rhs.sb);
template<class charT, class traits, class Allocator> void swap(basic_ostringstream<charT, traits, Allocator>& x, basic_ostringstream<charT, traits, Allocator>& y);
Effects: Equivalent to x.swap(y).
31.8.4.4 Member functions [ostringstream.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& t);
Constraints: is_convertible_v<const T&, basic_string_view<charT, traits>> is true.
Effects: Equivalent to: rdbuf()->str(t);