Linux上的c ++延迟输出

Question

I want some random characters to be printed to console and then deleted by "\\b" . After this I want to put my own variable so it will be looking like "randomizing". The problem is that it is happening too fast. I wanted to delay the output by using usleep or sleep function but when I'm using it, nothing is printed into console.
Short example:

#include <iostream>
#include <unistd.h>
using namespace std;

int main()
{
    char chars[]={'a','b','c','g','h','u','p','e','y'};
    for(int i=0; i<8; i++)
    {
        cout << chars[i];
        usleep(200000);
        cout << "\b";

    }
}

Answer 1

Problem is, std::cout is line-buffered . It stores all input in a buffer until a newline is encountered (or the program terminates). Use std::flush to flush std::cout explicitly:

cout << chars[i] << flush;

---

Notes:

• since C++11, multithreading and time are standardized. That brings the std::this_thread:sleep_for function with it, which you should use for a portable >= C++11 program:

   std::this_thread::sleep_for(std::chrono::milliseconds(200)); 

Answer 2

On many systems output is buffered.

To ensure that what you sent out to cout has really been flushed out of buffers you need to call

cout.flush();

before the sleep

Answer 3

Try my little program slowtty from github.

It allows you to simulate in a pty the behaviour of an old rs232c line, by delaying the output per character as stty(1) command allows to set the baudrate.

You call it with

$ slowtty
$ stty 1200
$

and the terminal begins to write characters at a slow pace (like a 1200baud line)