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From: "Jonas Jensen" <bones0_list AT hotmail DOT com>
To: "Brian J Ball" <bjball AT sep DOT com>, <cygwin AT sourceware DOT cygnus DOT com>
References: <NEBBINHAMKDDGPELHGEPAEBNCAAA DOT bjball AT sep DOT com>
Subject: Re: Post incrementers in arrays as function arguments
Date: Fri, 18 Aug 2000 20:14:01 +0200
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> This code has produced 3 different results on 4 systems.
> The second result was on the Cygwin B20 system
> [snip]
>    /*  This use of var++ in a function call is
> unpredictable */
>    print_array(array[i++],array[i++],array[i++]);
> }
> [snip]
> However, this works on some platforms and could become an error in porting
> software.

This is semi-documented behavior. Check out the infopage for gcc, this is
from the section "non-bugs":

>>>>>>>>>>>>>>>>>>>>>>>>>
* Making side effects happen in the same order as in some other
  compiler.

  It is never safe to depend on the order of evaluation of side
  effects.  For example, a function call like this may very well
  behave differently from one compiler to another:

       void func (int, int);

       int i = 2;
       func (i++, i++);

  There is no guarantee (in either the C or the C++ standard language
  definitions) that the increments will be evaluated in any
  particular order.  Either increment might happen first.  `func'
  might get the arguments `2, 3', or it might get `3, 2', or even
  `2, 2'.
<<<<<<<<<<<<<<<<<<<<<<<<<

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