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From: mcvoy@uwvax.UUCP
Newsgroups: comp.unix.questions
Subject: Re: Evaluating autoincrements in function calls
Message-ID: <3279@rsch.WISC.EDU>
Date: Thu, 26-Feb-87 14:02:49 EST
Article-I.D.: rsch.3279
Posted: Thu Feb 26 14:02:49 1987
Date-Received: Sat, 28-Feb-87 03:28:26 EST
References: <4707@brl-adm.ARPA>
Reply-To: mcvoy@rsch.WISC.EDU (Lawrence W. McVoy)
Organization: U of Wisconsin CS Dept
Lines: 20

In article <4707@brl-adm.ARPA> welch%UMASS.BITNET@wiscvm.wisc.EDU writes:
->In the second case the compiler is evaluating the arguments to
->the printf function right to left, including the autoincrement
->instructions, as it builds the stack.
-> 
->I don't want to be swamped with replies as to which set of results
->is correct but I would be interested to know if there is a standard
->which documents the correct behavior of argument evaluation.

This is explicitly undefined in the K&R definition, in other words, you
may not depend on any order of evalualtion when considering function
parameters.  My guess is that it was done as a efficiency/favour
for/to compilers/{compiler writers}.  Functions are done a lot;
it would be ill-advised to slow them down by enforcing evaluation
orders here.  It is unfortunate, though.  Inconsistencies suck.
-- 
Larry McVoy 	        mcvoy@rsch.wisc.edu, 
      		        {seismo, topaz, harvard, ihnp4, etc}!uwvax!mcvoy

"They're coming soon!  Quad-stated guru-gates!"