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Re: Please explain... [message #5400 is a reply to message #5253]

Mon, 27 November 1995 00:00

jlaw
Messages: 11
Registered: November 1995

Junior Member

In article 2gt@hammer.msfc.nasa.gov, mallozzi@ssl.msfc.nasa.gov writes:
> Can someone explain this to me?
>
> IDL> .r
> - x = 0 & y = 0
> - case 1 of
> - x and y: print, '1'
> - NOT x and y: print, '2'
> - x and NOT y: print, '3'
> - NOT x and NOT y: print, '4'
> - endcase
> - end
> % Compiled module: $MAIN$.
> % Case statement found no matches.
> % Execution halted at $MAIN$ </dev/tty( 1)> .

Well, I am getting
: x = 0
: print, NOT x
-1
: y = 0
: print, NOT x AND NOT y
-1

So your CASE does not evaluate to 1 here. < time out to look at online help >
The 'problem' is the implementation of Boolean types in IDL : It is done
bitwise, and even integers are true.. In fact there are no special
"TRUE" and "FALSE" values. Perhaps its best here to use an ELSE: label.
Are you sure all your booleans will always be 0 or 1?

f.

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[Message index]

		Please explain... By: mallozzi on Sun, 26 November 1995 00:00
		Re: Please explain... By: Ding Wu - see John Vo on Mon, 27 November 1995 00:00
		Re: Please explain... By: jlaw on Mon, 27 November 1995 00:00

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