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std::basic_ostream<CharT,Traits>::flush

From cppreference.com
< cpp‎ | io‎ | basic ostream
 
 
 
 
basic_ostream& flush();

Writes uncommitted changes to the underlying output sequence.

If rdbuf() is a null pointer, does nothing

Otherwise, behaves as an UnformattedOutputFunction (since C++11). After constructing and checking the sentry object, calls rdbuf()->pubsync(). If the call returns -1, calls setstate(badbit).

Contents

[edit] Parameters

(none)

[edit] Return value

*this

[edit] Exceptions

May throw std::ios_base::failure if exceptions()&badbit!=0.

[edit] Example

#include <thread>
#include <iostream>
#include <chrono>
void f()
{
    std::cout << "Output from thread...";
    std::this_thread::sleep_for(std::chrono::seconds(2));
    std::cout << "...thread calls flush()\n";
    std::cout.flush();
}
 
int main()
{
    std::thread t1(f);
    std::this_thread::sleep_for(std::chrono::seconds(1));
    std::clog << "Output from main\n";
    t1.join();
}

Output:

Output from main
Output from thread.....thread calls flush()

[edit] See also

invokes sync()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
synchronizes the buffers with the associated character sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
flushes the output stream
(function template) [edit]
outputs '\n' and flushes the output stream
(function template) [edit]
synchronizes with the underlying storage device
(public member function of std::basic_istream<CharT,Traits>) [edit]