Create a function to check for key press in Unix using ncurses

Question

I have been looking for an equivalent to kbhit() and I have read several forums on this subject, and the majority seem to suggest using ncurses.

How should I go about checking if a key is pressed in C++ using ncurses?

The function getch() provided by ncurses reads a character from the window. I would like to write a function that only checks if there is a key press and then I want to do getch().

Answer 1

You can use the nodelay() function to turn getch() into a non-blocking call, which returns ERR if no key-press is available. If a key-press is available, it is pulled from the input queue, but you can push it back onto the queue if you like with ungetch().

#include <ncurses.h>
#include <unistd.h>  /* only for sleep() */

int kbhit(void)
{
    int ch = getch();

    if (ch != ERR) {
        ungetch(ch);
        return 1;
    } else {
        return 0;
    }
}

int main(void)
{
    initscr();

    cbreak();
    noecho();
    nodelay(stdscr, TRUE);

    scrollok(stdscr, TRUE);
    while (1) {
        if (kbhit()) {
            printw("Key pressed! It was: %d\n", getch());
            refresh();
        } else {
            printw("No key pressed yet...\n");
            refresh();
            sleep(1);
        }
    }
}