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Checking the keyboard status in Unix

Posted on 1997-09-16
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Last Modified: 2006-11-17
Which function in Linux C can you use to check to see whether or not a keystroke is pending?  And more importantly, how can I use this function?
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Question by:Hexar
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msmits earned 800 total points
ID: 1254745
You should use the ioctl() system call on the file descriptor of the stdin.
On SUN Solaris, the manual page refers to the termio(7I) manual page which has a section about non-canonical mode input processing, which is what you want.
I believe I have some old code somewhere in which I did something like thing. I will try to find that for you, although it may use an older interface.

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by:msmits
ID: 1254746
#include <sys/ioctl.h>
#define fileno(p) ((p)->fd)

bool keypressed()
/* test whether a key if pressed */
{
      long l;
      int fd;

      fd = fileno(stdin);

      if (ioctl(fd, FIONREAD, &l) != -1)
            if (l > 0)
                  return TRUE;
      return FALSE;
}

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