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From: burris@ihuxz.ATT.COM (Burris)
Newsgroups: comp.sys.atari.st
Subject: Re: Megamax bug or crappy C ?
Message-ID: <2084@ihuxz.ATT.COM>
Date: Fri, 22-May-87 09:05:04 EDT
Article-I.D.: ihuxz.2084
Posted: Fri May 22 09:05:04 1987
Date-Received: Sat, 23-May-87 16:32:04 EDT
References: <756@klipper.cs.vu.nl>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 39
Summary: Here's what K & R say.

In article <756@klipper.cs.vu.nl>, tulp@cs.vu.nl (Eduard Tulp) writes:

> Try this piece of code with the Megamax C compiler.  I am not sure whether 
> this  is a bug...

> 
> main()
> 
> {
 	.
	.
	.

> 
>   while (i > 0)
>         array[i - 1] = array[i--] - 1;              /* Trouble here.  */
	.
	.
	.
>   while (i < 6)
>         array[i + 1] = array[i++] + 1;            /* And trouble here. */
	.
	.
	.
> }


Function calls, nested assignments, and increment and decrement operators cause
"side effects"...

...One unhappy situation is typified by the statement

	a[ i ] = i++;

...When side effects (assignment to actual variables) takes place is left to
the discretion of the compiler...

The moral of this discussion is that writing code which depends on order
of evaluation is a bad programming practice in any language...