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Logical vs. Bitwise boolean operators [message #29164]

Fri, 01 February 2002 08:04

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

Fortran has the logical boolean operators .AND., .OR., and .NOT., and I
naively expected the correspondingly named IDL operators to be the same.
However, in IDL, those are bitwise operators, rather than logical ones
(my copy of the manual just calls them 'boolean', without specifying
whether they are logical or bitwise). As a result, the following code
did not do what I expected:

IF (!D.FLAGS AND 8) AND (ratio LE minrat) THEN BEGIN

I can always code around this limitation. The solution I came up with
was to change it to:

IF ((!D.FLAGS AND 8) EQ 8) AND (ratio LE minrat) THEN BEGIN

However, it seems to me that there should be a better way to do this.

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