[ospanstream]

# 31 Input/output library [[input.output]](./#input.output)

## 31.9 Span-based streams [[span.streams]](span.streams#ospanstream)

### 31.9.5 Class template basic_ospanstream [ospanstream]

#### [31.9.5.1](#general) General [[ospanstream.general]](ospanstream.general)

[🔗](#lib:basic_ospanstream)

namespace std {template<class charT, class traits = char_traits<charT>>class basic_ospanstream : 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; // [[ospanstream.cons]](#cons "31.9.5.2 Constructors"), constructorsexplicit basic_ospanstream(std::span<charT> s,
 ios_base::openmode which = ios_base::out);
 basic_ospanstream(const basic_ospanstream&) = delete;
 basic_ospanstream(basic_ospanstream&& rhs);

 basic_ospanstream& operator=(const basic_ospanstream&) = delete;
 basic_ospanstream& operator=(basic_ospanstream&& rhs); // [[ospanstream.swap]](#swap "31.9.5.3 Swap"), swapvoid swap(basic_ospanstream& rhs); // [[ospanstream.members]](#members "31.9.5.4 Member functions"), member functions basic_spanbuf<charT, traits>* rdbuf() const noexcept;

 std::span<charT> span() const noexcept; void span(std::span<charT> s) noexcept; private: basic_spanbuf<charT, traits> *sb*; // *exposition only*};}

#### [31.9.5.2](#cons) Constructors [[ospanstream.cons]](ospanstream.cons)

[🔗](#lib:basic_ospanstream,constructor)

`explicit basic_ospanstream(std::span<charT> s,
                           ios_base::openmode which = ios_base::out);
`

[1](#cons-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10635)

*Effects*: Initializes the base class withbasic_ostream<charT, traits>(addressof(*sb*)) and *sb* withbasic_spanbuf<charT, traits>(s, which | ios_base​::​out) ([[spanbuf.cons]](spanbuf.cons "31.9.3.2 Constructors"))[.](#cons-1.sentence-1)

[🔗](#lib:basic_ospanstream,constructor_)

`basic_ospanstream(basic_ospanstream&& rhs) noexcept;
`

[2](#cons-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10649)

*Effects*: Initializes the base class with std​::​move(rhs) and *sb* with std​::​move(rhs.*sb*)[.](#cons-2.sentence-1)

Next, basic_ostream<charT, traits>​::​set_rdbuf(addressof(*sb*)) is called to install the contained basic_spanbuf[.](#cons-2.sentence-2)

#### [31.9.5.3](#swap) Swap [[ospanstream.swap]](ospanstream.swap)

[🔗](#lib:swap,basic_ospanstream)

`void swap(basic_ospanstream& rhs);
`

[1](#swap-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10665)

*Effects*: Equivalent to:basic_ostream<charT, traits>::swap(rhs);*sb*.swap(rhs.*sb*);

[🔗](#lib:swap,basic_ospanstream_)

`template<class charT, class traits>
  void swap(basic_ospanstream<charT, traits>& x, basic_ospanstream<charT, traits>& y);
`

[2](#swap-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10681)

*Effects*: Equivalent to x.swap(y)[.](#swap-2.sentence-1)

#### [31.9.5.4](#members) Member functions [[ospanstream.members]](ospanstream.members)

[🔗](#lib:rdbuf,basic_ospanstream)

`basic_spanbuf<charT, traits>* rdbuf() const noexcept;
`

[1](#members-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10694)

*Effects*: Equivalent to:return const_cast<basic_spanbuf<charT, traits>*>(addressof(*sb*));

[🔗](#lib:span,basic_ospanstream)

`std::span<charT> span() const noexcept;
`

[2](#members-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10708)

*Effects*: Equivalent to: return rdbuf()->span();

[🔗](#lib:span,basic_ospanstream_)

`void span(std::span<charT> s) noexcept;
`

[3](#members-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L10719)

*Effects*: Equivalent to rdbuf()->span(s)[.](#members-3.sentence-1)