std::basic_ispanstream<CharT,Traits>::span

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Input/output library

I/O manipulators
Print functions(C++23)
C-style I/O
Buffers
basic_streambuf
basic_filebuf
basic_stringbuf
basic_spanbuf (C++23)
strstreambuf (C++98/26*)
basic_syncbuf (C++20)
Streams
Abstractions
ios_base
basic_ios
basic_istream
basic_ostream
basic_iostream
File I/O
basic_ifstream
basic_ofstream
basic_fstream
String I/O
basic_istringstream
basic_ostringstream
basic_stringstream
Array I/O
basic_ispanstream (C++23)
basic_ospanstream (C++23)
basic_spanstream (C++23)
istrstream (C++98/26*)
ostrstream (C++98/26*)
strstream (C++98/26*)
Synchronized Output
basic_osyncstream (C++20)
Types
streamoff
streamsize
fpos
Error category interface
iostream_category (C++11)
io_errc (C++11)

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std::basic_ispanstream

Member functions
basic_ispanstream::basic_ispanstream
basic_ispanstream::operator=
basic_ispanstream::swap
basic_ispanstream::rdbuf
Underlying buffer operations
basic_ispanstream::span
Non-member functions
swap(std::basic_ipanstream)

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std::span<const CharT> span()constnoexcept;	(1)	(since C++23)
void span(std::span<CharT> s)noexcept;	(2)	(since C++23)
template<class SpanLike> void span( SpanLike&& r)noexcept;	(3)	(since C++23)

1) Gets aspan referencing the written area ifstd::ios_base::out is set in the open mode of the wrappedstd::basic_spanbuf, or aspan referencing the underlying buffer otherwise.

2) Makes the wrappedstd::basic_spanbuf perform I/O on the buffer referenced bys.

3) Same as(2), except thats is obtained as if by
std::span<const CharT> cs{std::forward<SpanLike>(r)};
std::span<CharT> s{const_cast<CharT*>(cs.data()), cs.size()};
. This overload participates in overload resolution only ifSpanLike modelsborrowed_range,std::convertible_to<SpanLike,std::span<CharT>> isfalse, andstd::convertible_to<SpanLike,std::span<const CharT>> istrue.

[edit]Parameters

s	-	std::span referencing the storage to be use as the new underlying buffer of stream
r	-	`borrowed_range` to be use as the new underlying buffer of stream

[edit]Return value

1) Astd::span referencing the underlying buffer or written area, depending on the open mode of the wrappedstd::basic_spanbuf.

2,3) (none)

[edit]Example

Run this code

#include <cassert>#include <iostream>#include <span>#include <spanstream> int main(){char out_buf[16];std::ospanstream ost{std::span<char>{out_buf}};    ost<<"C++"<<' '<<23<<'\0';// note explicit null-terminationauto sp= ost.span();assert(        sp[0]=='C'&& sp[1]=='+'&& sp[2]=='+'&&        sp[3]==' '&& sp[4]=='2'&& sp[5]=='3'&&        sp[6]=='\0');std::cout<<"sp.data(): ["<< sp.data()<<"]\n";std::cout<<"out_buf: ["<< out_buf<<"]\n";// spanstream uses out_buf as internal storage, no allocationsassert(static_cast<char*>(out_buf)== sp.data()); constchar in_buf[]="X Y 42";std::ispanstream ist{std::span<constchar>{in_buf}};assert(static_cast<constchar*>(in_buf)== ist.span().data());char c;    ist>> c;assert(c=='X');    ist>> c;assert(c=='Y');int i;    ist>> i;assert(i==42);    ist>> i;// buffer is exhaustedassert(!ist);}