Using kbhit() and getch() on Linux

Question

On Windows, I have the following code to look for input without interrupting the loop:

#include <conio.h>
#include <Windows.h>
#include <iostream>

int main()
{
    while (true)
    {
        if (_kbhit())
        {
            if (_getch() == 'g')
            {
                std::cout << "You pressed G" << std::endl;
            }
        }
        Sleep(500);
        std::cout << "Running" << std::endl;
    }
}

However, seeing that there is no conio.h, whats the simplest way of achieving this very same thing on Linux?

Answer 1

If your linux has no conio.h that supports kbhit() you can look here for Morgan Mattews's code to provide kbhit() functionality in a way compatible with any POSIX compliant system.

As the trick desactivate buffering at termios level, it should also solve the getchar() issue as demonstrated here.

Answer 2

The ncurses howto cited above can be helpful. Here is an example illustrating how ncurses could be used like the conio example:

#include <ncurses.h>

int
main()
{
    initscr();
    cbreak();
    noecho();
    scrollok(stdscr, TRUE);
    nodelay(stdscr, TRUE);
    while (true) {
        if (getch() == 'g') {
            printw("You pressed G\n");
        }
        napms(500);
        printw("Running\n");
    }
}

Note that with ncurses, the iostream header is not used. That is because mixing stdio with ncurses can have unexpected results.

ncurses, by the way, defines TRUE and FALSE. A correctly configured ncurses will use the same data-type for ncurses' bool as the C++ compiler used for configuring ncurses.