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std::basic_osyncstream<CharT,Traits,Allocator>:: emit

From cppreference.net
C++
Input/output library
std::basic_osyncstream
void emit ( ) ;

Emits all buffered output and executes any pending flushes, by calling emit() on the underlying std::basic_syncbuf .

Parameters

(none)

Example

Run this code 
#include <iostream>
#include <syncstream>
int main()
{
    {
        std::osyncstream bout(std::cout);
        bout << "Hello," << '\n'; // no flush
        bout.emit(); // characters transferred; cout not flushed
        bout << "World!" << std::endl; // flush noted; cout not flushed
        bout.emit(); // characters transferred; cout flushed
        bout << "Greetings." << '\n'; // no flush
    } // destructor calls emit(): characters transferred; cout not flushed
    // emit can be used for local exception-handling on the wrapped stream
    std::osyncstream bout(std::cout);
    bout << "Hello, " << "World!" << '\n';
    try
    {
        bout.emit();
    }
    catch (...)
    {
        // handle exceptions
    }
}

Output: 

Hello,
World!
Greetings.
Hello, World!

See also

destroys the basic_osyncstream and emits its internal buffer
(public member function)
atomically transmits the entire internal buffer to the wrapped streambuf
(public member function of std::basic_syncbuf<CharT,Traits,Allocator> )