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From: edw@ius2.cs.cmu.edu.UUCP
Newsgroups: comp.lang.c
Subject: Re: boolean function to tell if a key has been pressed
Message-ID: <1073@ius2.cs.cmu.edu>
Date: Sat, 21-Mar-87 16:37:57 EST
Article-I.D.: ius2.1073
Posted: Sat Mar 21 16:37:57 1987
Date-Received: Sun, 22-Mar-87 17:38:14 EST
References: <10260@topaz.RUTGERS.EDU> <523@thumper.UUCP>
Organization: Carnegie-Mellon University, CS/RI
Lines: 31


 In article <10260@topaz.RUTGERS.EDU>, whoffman@topaz.UUCP writes:
 > 
 > Hello,
 > 
 >    I am seeking a way to tell whether or not a key has been pressed on
 > a keyboard. i.e something like this:
 >   
 >      while (1)
 >      { ...statements....
 >       if "a key has been pressed" {...statements}
 >       ...statements...}
 > 
 > the problem i keep running into is that getc,getchar etc..all WAIT for
 > a key to be pressed. I would just like to see IF one has been pressed.
 > Any help on this would be greatly appreciated. Thanks in advance...
 > 
 > William R. Hoffman

  If you are on a unix os you can make a call to "select" and it will
tell you whether a file descriptor or list of files descriptor are ready
to read from, write to, or have excecption pending (See manual entry
for select for more details.)   Note also you can get the file descriptor
for a pointer to a file (FILE *fp)  with the macro fileno which is
defined in stdio.h.
   Also, if you are on a Unix os, you will want to make the appropriate
call to ioctl or stty so that characters are made available to your process
as soon as they are type, instead of buffering them until a new line is
type from the terminal (cbreak on or off, one of the two). 

					Eddie Wyatt