std::basic_osyncstream<CharT,Traits,Allocator>::operator=

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

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Named requirements

Feature test macros (C++20)

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Concepts library (C++20)

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Diagnostics library

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Ranges library (C++20)

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Technical specifications

Symbols index

External libraries

 

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

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basic_ifstream

basic_ofstream

basic_fstream

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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)

 

std::basic_osyncstream

Public member functions

basic_osyncstream::basic_osyncstream (C++20)

basic_osyncstream::operator= (C++20)

basic_osyncstream::~basic_osyncstream (C++20)

basic_osyncstream::rdbuf (C++20)

basic_osyncstream::get_wrapped (C++20)

basic_osyncstream::emit (C++20)

 

basic_osyncstream& operator=( std::basic_osyncstream&& other );		(since C++20)

Move-assigns a synchronized output stream:

Move-assigns the wrapped std::basic_syncbuf from the corresponding member of other (after this move-assignment, other.get_wrapped() returns a null pointer and destruction of other produces no output; any pending buffered output will be emitted) and move-assigns the base std::basic_ostream (this swaps all stream state variables except for rdbuf between *this and other)

Parameters

other

-

another synchronized output stream to move from

Return value

*this

Example

Run this code

#include <iomanip>
#include <iostream>
#include <sstream>
#include <syncstream>
#include <utility>
 
int main()
{
    std::osyncstream out(std::cout);
    out << "test\n";
    std::ostringstream str_out;
    std::osyncstream{str_out} = std::move(out); // Note that out is emitted here
    std::cout << "str_out = " << std::quoted(str_out.view()) << '\n';
}

Output:

test
str_out = ""

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3867	C++20	the move assignment operator was noexcept, but std::basic_syncbuf's move assignment operator is not	removed noexcept

See also

(constructor)	constructs a basic_osyncstream object (public member function)
(destructor)	destroys the basic_osyncstream and emits its internal buffer (public member function)
emit	calls emit() on the underlying basic_syncbuf to transmit its internal data to the final destination (public member function)