c++bufferflagsflushmanipulators

How to flush buffer manually?

this is same Question but not answered properly.

Code

#include<iostream>
int main()
{
    char ch='a';
    std::cout<<ch;
}

Output

a

so here only one character in output stream which leads to buffer. so buffer is not full still it shows ouput on screen. Means buffer is flushed automatically.

so please give example where buffer not flushes automatically and we have to use the manipulator flag flush.

Solution

  • You can see whether your stream is buffered by sleeping between outputs, e.g.:

    #include <iostream>
#include <thread>

int main()
{
    for (int i = 0; i < 50; i++)
    {
        char ch = 'a';
        std::cout << ch << "\n";
        std::this_thread::sleep_for(std::chrono::milliseconds(500));
    }
}

    On some platforms you might need to enable buffering on stdout by calling setvbuf:

    std::setvbuf(stdout, nullptr, _IOFBF, BUFSIZ);