Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.3 alpha 4/15/85; site ucbvax.ARPA
Path: utzoo!watmath!clyde!cbosgd!ucbvax!info-vax
From: info-vax@ucbvax.ARPA
Newsgroups: fa.info-vax
Subject: Single character input to a C program
Message-ID: <8416@ucbvax.ARPA>
Date: Sun, 23-Jun-85 13:54:23 EDT
Article-I.D.: ucbvax.8416
Posted: Sun Jun 23 13:54:23 1985
Date-Received: Mon, 24-Jun-85 06:37:13 EDT
Sender: daemon@ucbvax.ARPA
Organization: University of California at Berkeley
Lines: 30

From: John M Sellens <jmsellens%waterloo.csnet@csnet-relay.ARPA>

Under VMS 4.1, I want to write a C program that can obtain single character
input from the keyboard, without any editing, and without waiting for the
user to press return.  The character should not be echoed on the screen,
my program will do all the necessary echoing.

I am using the SMG$ routines for screen output.  I tried using
SMG$ENABLE_UNSOLICITED_INPUT to enable a routine that will be activated
each time a key is pressed.  I tried to make it reasonably intelligent,
but I seemed to have very little luck.  One problem that I ran into was
that I couldn't convince it to accept an escape character without a
following escape sequence (our program uses escape to indicate "undo"
or "stop what I'm doing").

I would also like to be able to inquire whather or not a character or
characters is waiting (or alternatively, do something like a non-blocking
getchar()).

There is only a small amount of VMS expertise here a Waterloo, so asking
around hasn't been too successful.  I will greatly appreciate any help
that you can offer me.

Thanks!

John

UUCP:  {decvax|utzoo|ihnp4|allegra|clyde}!watmath!jmsellens
CSNET: jmsellens%watmath@waterloo.csnet
ARPA:  jmsellens%watmath%waterloo.csnet@csnet-relay.arpa