Need Non-Blocking Terminal Input Fun

[bolte at umn-cs.UUCP]

	There is a very simple way to do what you want. The select (2) call
	can be used to wait for input from a file descriptor or return after
	a certain amount of time.

	Here is a complete program to do just that. Note: it is for BSD 4.2

			Scott Bolte
			U. of Minnesota  A.I. Lab
			ihnp4!umn-cs!bolte

================================================================================

#include <sys/time.h>
#include <stdio.h>
#include <fcntl.h>

main(argc,argv)
 char *argv[];
{
	int	ifd,flag;
	struct	timeval	tim;

	tim.tv_sec = (argc>1)?atoi(argv[1]):3; 	/* wait for argv[1] seconds */
						/* default is 9		    */
	tim.tv_usec = 0;

	ifd = 1<<0;		/* Since stdin is file descriptor 0 only shift
				   by zero. To wait for file descriptor x as
				   well add the line 'ifd |= 1<<x'          */

	printf("You have %d seconds to type something\n",tim.tv_sec);
	fflush(stdin);		/* clear all previous, unprocessed input      */
	fflush(stdout);		/* insure you get message before timer starts */

	if( select(2,&ifd,0,0,&tim) == 0){
		printf("Nothing was typed before time ran out.\n");
	} else {
		while( getchar() != '\n');	/* clear what was typed */
		printf("Something was typed.\n");
	}
}