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

 

C++

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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)

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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)

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streamoff

streamsize

fpos

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iostream_category (C++11)

io_errc (C++11)

 

std::basic_spanstream

Member functions

basic_spanstream::basic_spanstream (C++23)

basic_spanstream::operator= (C++23)

basic_spanstream::swap (C++23)

basic_spanstream::rdbuf (C++23)

Underlying buffer operations

basic_spanstream::span (C++23)

Non-member functions

swap(std::basic_spanstream) (C++23)

 

std::span<CharT> span()constnoexcept;	(1)	(since C++23)
void span(std::span<CharT> s )noexcept;	(2)	(since C++23)

1) Gets a span referencing the written area if std::ios_base::out is set in the open mode of the wrapped std::basic_spanbuf, or a span referencing the underlying buffer otherwise.

2) Makes the wrapped std::basic_spanbuf perform I/O on the buffer referenced by s.

Parameters

s

-

std::span referencing the storage to be use as the new underlying buffer of stream

Return value

1) A std::span referencing the underlying buffer or written area, depending on the open mode of the wrapped std::basic_spanbuf.

2) (none)

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);}

Output:

sp.data(): [C++ 23] out_buf: [C++ 23]

See also

span	obtains or initializes an underlying buffer according to mode (public member function of std::basic_spanbuf<CharT,Traits>)