Path: utzoo!attcan!uunet!zephyr.ens.tek.com!tektronix!reed!reeder
From: reeder@reed.UUCP (Doug Reeder)
Newsgroups: comp.lang.pascal
Subject: Re: Pascal Assignment statements
Message-ID: <13382@reed.UUCP>
Date: 7 Oct 89 11:46:28 GMT
References: <723@chudich.co.rmit.oz>
Reply-To: reeder@reed.UUCP (Doug Reeder)
Organization: Reed College, Portland OR
Lines: 30

In article <723@chudich.co.rmit.oz> rcosw@koel.co.rmit.oz (Simon Wail) writes:

>Q. Is all address calculations of the assignment variable performed before
>   the expression on the R.H.S. is evaluated???

>Some examples that cause problems :

>x[a+b] := f;

>	where "f" is a function that modifies the global variables "a" and "b"
>	which are used to index the array on the L.H.S.  Is the index to the
>	array calculated before "f" is called???


From "Pascal For Programmers" by Lecarme & Nebutt (McGraw-Hill 1984) p27-28:

"The order in which the two sides of the assignment statement are evaluated
is implementation-dependent; i.e., a correct program must not depend on this
order."

Also, the terms in an expression are evaluated in an implementation-defined
manner. Thus, you can do whatever you like and don't even have to always do 
the same thing.  The book, by the way, is an excellent reference for the
experienced programmer.  I consult mine all the time.

-- 
Doug Reeder                          USENET: ...!tektronix!reed!reeder
Box 722 Reed College                 BITNET: reeder@reed.BITNET
Portland, OR 97202                from ARPA: tektronix!reed!reeder@berkeley.EDU
(503) 777-1551                  "A blaster can point two ways."  -Salvor Hardin