_kbhit

A function that returns a non-zero value when a character is waiting in stdin. Used to test whether a user has pressed a key. https://www.flipcode.com/archives/_kbhit_for_Linux.shtml

#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;
    }
}