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From: mcastle@mcs213f.cs.umr.edu (Mike Castle (Nexus))
Newsgroups: comp.lang.pascal
Subject: Re: Help Me!!! What's wrong with this simple problem?
Message-ID: <1759@umriscc.isc.umr.edu>
Date: 28 Nov 90 04:48:47 GMT
References: <527@shum.UUCP> <19956@oolong.la.locus.com> <28893@shamash.cdc.com>
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In article <28893@shamash.cdc.com> mpe@shamash.UUCP (Mike Ebsen) writes:
>What's wrong with this problem in Turbo Pascal 5.0...
>
>      Program test;
>      var
>        i : integer;
>        j : word;
>      begin
>        j:=3;
>        i:=j-10;
>        writeln(j,'     ',i);
>      end.
>
>My compiler tells me that the assignment of -7 into i (an integer) 
>is an error.

Well, it first tries to evaluate j-10.  Since j is a word, it tries to 
evaluate j-10 as a word.  A word ranges from 0..65535.  So -7 is an error.
That's the way pascal works, I assume, as opposed to an error.

If it put 3 into i first, and THEN subtracted 7, no problem, but it doesn't
work that way.

You can defeat this by putting in the compiler directive {$R-} or changing
it range checking to off from the options menu, but I wouldn't advise it.
At least, not until you've gotten all the other bugs worked out and you wanted
to save some speed and size.

By turning off the range checking, I got it to print out 3 and -7, but that's
no guarantee it would work all the time.

In short, try this:

    i := j;
    i := i-7;

Always pays to look up the run time errors in the manual too....  :->
-- 
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