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copied!<p>If you are on a POSIX operating system, you can set the terminal to be unbuffered using the functions and structures declared in <code>termios.h</code>. Basically you need to disable canonical input, and setup the terminal for non-canonical mode. These are some links that can help you with understanding the difference between the two terminal modes:</p> <ol> <li><p><a href="http://www.gnu.org/software/libc/manual/html_node/Noncanonical-Input.html" rel="nofollow noreferrer">Noncanonical Input</a> (from the libc manual)</p> <blockquote> <p>In <em>non-canonical</em> input mode, the special editing characters such as ERASE and KILL are ignored. The system facilities for the user to edit input are disabled in noncanonical mode, so that all input characters (unless they are special for signal or flow-control purposes) are passed to the application program exactly as typed. It is up to the application program to give the user ways to edit the input, if appropriate.</p> </blockquote></li> <li><p><a href="https://stackoverflow.com/questions/358342/canonical-vs-non-canonical-terminal-input">Canonical vs. non-canonical terminal input</a></p> <blockquote> <p>For <em>canonical</em> input - think shell; actually, think good old-fashioned Bourne shell, since Bash and relatives have command-line editing. You type a line of input; if you make a mistake, you use the erase character (default is backspace, usually; sometimes DEL) to erase the previous character ... For <em>non-canonical</em> input - think vi or vim or ... you press a character, and it is immediately available to the program. You aren't held up until you hit return.</p> </blockquote></li> <li><p><a href="http://pubs.opengroup.org/onlinepubs/7908799/xbd/termios.html" rel="nofollow noreferrer">Description of Terminal Interface</a></p> <blockquote> <p>This chapter describes a general terminal interface that is provided to control asynchronous communications ports. It is implementation-dependent whether it supports network connections or synchronous ports or both.</p> </blockquote></li> </ol> <p>In essence though, the issue you're encountering is not with the C++ iostream interface itself, but rather has to-do with how the controlling terminal that the C++ iostream interface is reading from has been setup. Thus taking advantage of unbuffered I/O is going to be a platform-dependent operation, and will differ dependending on whether you're using Windows, or an actual POSIX-compliant platform (this includes POSIX-environments for Windows such as Cygwin).</p> <p>If you find that messing around with the terminal settings is too much of a problem, you can also look into a cross-platform <a href="http://en.wikipedia.org/wiki/Curses_(programming_library)" rel="nofollow noreferrer">curses programming library</a> such as <a href="http://pdcurses.sourceforge.net/" rel="nofollow noreferrer">PDCurses</a> that will abstract most of the complexities of the underlying terminal types.</p>

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