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From: wsmith@uiucdcsb.cs.uiuc.edu
Newsgroups: net.lang.c
Subject: Re: Evaluation of function arguments (w
Message-ID: <139200035@uiucdcsb>
Date: Fri, 26-Sep-86 15:53:00 EDT
Article-I.D.: uiucdcsb.139200035
Posted: Fri Sep 26 15:53:00 1986
Date-Received: Tue, 30-Sep-86 05:02:37 EDT
References: <3966@brl-smoke.ARPA>
Lines: 53
Nf-ID: #R:brl-smoke.ARPA:3966:uiucdcsb:139200035:000:888
Nf-From: uiucdcsb.cs.uiuc.edu!wsmith    Sep 26 14:53:00 1986


>int i;
> i = 0;
>f ( i++, i++, i++);
>write(i);
> f( a,b,c) int a,b,c;
>  write (a,b,c);
>
Because the expression being used in your program is un-defined in
the C language, lint complains about such non-sensical programs,
saying evaluation order undefined.

Your program could be translated into something like this:
	load   r0,i
	pusharg r0
	load   r1,i
	pusharg r1
	load   r2,i
	pusharg r2
	inc    r2
	load   i,r2
	inc    r1
	load   i,r1
	inc    r0
	load   i,r0
	call	f
	....


In which case, the program would print out:
0 0 0
1
Another possibility that will probably generate fewer flames is:
0 0 0
3

I don't know of a compiler that does such nonsense, but I think one could.

A safer program is
main()
{
int i;
f(g(&i),g(&i),g(&i));
write(i);
}
f(a,b,c)  int a,b,c;
{ write (a,b,c); }
g(pi) int * pi;  
{ return( (*pi)++ ); }

Bill Smith
ihnp4!uiucdcs!wsmith
wsmith@a.cs.uiuc.edu