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Path: utzoo!linus!philabs!cmcl2!rocky2!cubsvax!wu1!rf
From: rf@wu1.UUCP
Newsgroups: net.lang.c
Subject: Re: Need Help: 1-char input in C
Message-ID: <216@wu1.UUCP>
Date: Tue, 27-Dec-83 18:43:14 EST
Article-I.D.: wu1.216
Posted: Tue Dec 27 18:43:14 1983
Date-Received: Fri, 30-Dec-83 00:23:24 EST
References: <464@ihuxn.UUCP>, <415@bbncca.ARPA>
Organization: Western Union Telegraph, Mahwah, NJ
Lines: 55

The following will work only if you controlling terminal is not
initially in cbreak mode:

   system("stty cbreak");
   c=getchar();
   system("stty -cbreak");

Raw mode should be avoided, since it will sometimes return
characters with whose values are either less than zero or
greater than 127.  A switch to raw mode may also cause the
terminal to lose some output, since raw mode disables the
XON/XOFF protocol.

You probably want to enable cbreak mode when you begin your
program and end it when you're done.  The following less
portable code is a hacked version of something which does work
and is much faseter than system("stty . . .");.  It probably
works, but has not been tested.

struct sgttyb otsgb;

/* iniline -- initialize line

This routine stores the terminal characteristics of stdin in
otsgb and turns on cbreak mode.   If stdin's file is not a
terminal (perhaps for testing,) iniline does nothing.

 */
iniline() {
   struct sgttyb ntsgb;
   
   if (isatty(fileno(stdin))) {
      ioctl(fileno(stdin), TIOCGETP, &otsgb);
      ntsgb = otsgb;
      ntsgb.sg_flags |= CBREAK;
      ioctl(fileno(stdin), TIOCSETP, &ntsgb);
      }
   }

/* resetline -- reset line characteristics

This routine restores the terminal characteristics of stdin,
which should be preserved in otsgb.  If the line's file is not a
terminal (perhaps for testing,) resetline does nothing.

 */
resetline() {
   if (isatty(fileno(stdin))) {
      ioctl(fileno(stdin), TIOCSETP, &otsgb);
      }
   }


			Randolph Fritz
			Western Union Telegraph