From: Erik Max Francis <max AT alcyone DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: boolean
Date: Wed, 07 May 1997 20:59:57 -0700
Organization: Alcyone Systems
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lab wrote:

> Is   enum Boolean {false,true};
> 
>                  Supported in djgpp?......In Borland this ok..

It is not standard anything.

I used to use Borland C (Turbo C 2.0, in fact).  It was a good compiler,
but a lot of the extensions and extra functionality included is not
rigidly distinguished.  (e.g., "This feature is not ANSI C and may not be
available in other compilers.")  For Turbo C 2.0, in particular, there
were some features which were _listed_ as being ANSI C compliant but in
fact were not.

In C++ 2.1 (which DJGPP supports) there is the fundamental bool datatype,
with keywords (not enum names) true and false.  Implicitly converting back
and forth between int and bool will do the right thing; that is, (bool) 2
is true.

You can at least get the basic functionality by using something like the
following:

    #ifdef BOOL
    typedef int bool;
    #define false 0
    #define true 1
    #endif

If you're using a compiler which supports bool, then everything just works
in the rest of your program.  If it doesn't, then all you need to do
define BOOL in your command line parameters or your perfix file (if you're
using Think C/CodeWarrior).

This won't get you the automatic coercion, but it will get you the
implicit typecasting in C++ (where int i = true wouldn't work if true were
an enum name).

-- 
       Erik Max Francis, &tSftDotIotE / email / max AT alcyone DOT com
                     Alcyone Systems /   web / http://www.alcyone.com/max/
San Jose, California, United States /  icbm / 37 20 07 N  121 53 38 W
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