From:	"John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: F6 and fgets loop goes mad
Date:	Sun, 08 Mar 1998 12:48:41 -0500
Organization:	Two pounds of chaos and a pinch of salt.
Lines:	36
Message-ID:	<3502D9F9.46FC@cs.com>
References:	<34FFB2DB DOT 4B11 AT sainet DOT net>
NNTP-Posting-Host:	ppp229.cs.com
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

shifter wrote:
> 
> I have a password program that works fine until I press F6 then ENTER
> and it goes into a wild loop ignoring fgets.
> Is this a bug in DJGPP?

F6 is an extended key and will cause stdio routines to barf if you don't
trap it correctly.

Extended keys return two key values:  ASCII 0 to signal an extended key,
followed by the code for the key itself.  Most compiler manuals and some
textbooks give listings of the extended keys.

I just ran a quick test and it appears that stdio routines interpret
some extended keys like F6 as EOF characters.  This could be the cause
of your problems.

It is absolutely not a good idea to use stdio routines in programs that
depend on robust keyboard input.  This applies no matter what compiler
you use.  The functions in <conio.h> are much better at trapping
extended keys; at least you get the opportunity to detect them and
respond appropriately.  The conio functions also make it possible to do
things like not echo the keystrokes when entering a password.

For really robust work, use <pc.h> and the getkey() function, which
returns both normal and extended keystrokes as special codes whose
symbolic names are defined in <keys.h>.  I suggest you look them up.

Hope this helps!
-- 
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