Numeric problem in BlackBox 1.4

From: [at]} <Wojtek>
Date: Sat, 15 Feb 2003 22:52:02 -0500 (EST)

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Hello:

  the following code illustrates a numeric problem with CP
compiler, version BlackBox 1.4 unpatched. The comparison
yields either TRUE or FALSE depending on the precision
of the REAL number. (Try exchanging the order of the
lines where the REAL variable is assigned). The language
report does not say anything about such a mixed comparison
(realVar = intVar). In the spirit of robustness I would
rather prefer that this expression does not compile at all.
ENTIER should be necessary, rather than relying on
rounding the REAL variable in some implicit way.

Excuse me if this was already patched.

Wojtek Skulski skulski{([at]})nowhere.xy

MODULE TestEqual;
IMPORT StdLog;
PROCEDURE Test*;
        VAR
        tst: BOOLEAN;
        r: REAL; long: LONGINT; int: INTEGER;
BEGIN
        long := 1; int := 1;
        r := 1.000000000000000001; (* TRUE*)
        r := 1.0000000000001; (* FALSE*)
        tst := (r = long);
        StdLog.String("Real = long: ");
        StdLog.Bool (tst); StdLog.Ln;
        tst := (r = int);
        StdLog.String("Real = int: ");
        StdLog.Bool (tst); StdLog.Ln;
END Test;
END TestEqual.

TestEqual.Test

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Received on Sun Feb 16 2003 - 04:52:02 UTC