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From: defaria@hpcupt3.cup.hp.com (Andy DeFaria)
Newsgroups: comp.lang.pascal
Subject: Re: passing two variables
Message-ID: <45670024@hpcupt3.cup.hp.com>
Date: 24 Jun 91 22:35:26 GMT
References: <1991Jun21.144356.19598@javelin.sim.es.com>
Organization: Hewlett Packard, Cupertino
Lines: 44

>/ hpcupt3:comp.lang.pascal / tpehrson@javelin.sim.es.com (Tim Clinkenpeel) /  7:43 am  Jun 21, 1991 /
>i would like a function to pass back two variables.  is this possible?  
>below is an example of what i'd like to accomplish:
>
>cx,cy :=checkvalid(cx+offset,cy+offset);

I'll take  a stab here.  Assuming  that the function  name checkvalid is to
indeed check if something is valid then why not:

function checkvalid (var parm1 : integer; 
                     var parm2 : integer) : boolean;

Then you could:

	if not checkvalid (foo, bar) then
	   begin
	   writeln ('Error has occured');
	   halt
	   end;
	else
	   { Other processing }

This allows you to return a result specifying whether things are OK as well
as modify the parameters.   Ah I  see where  your probably having problems!
You  trying to  pass an  expression   and the  compiler doesn't   allow var
parameters  to be  expressions  - it want  a bonified  variable that it can
modify.  You'll need to:

var
   cx    : integer;
   cy    : integer;
   cxnew : integer;
   cynew : integer;

begin
   ...

   cxnew := cx + offset;
   cynew := cy + offset;

   if checkvalid (cxnew, cynew) then
      { process }
   else
      writeln ('Error');