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Passing zero as a Parameter/ NOT KEYWORD_SET [message #16121]

Mon, 28 June 1999 00:00

Grady Daub
Messages: 22
Registered: June 1999

Junior Member

How can I pass the number zero as a parameter, without the
function/subroutine thinking that the parameter is not set?

For example:

;code
pro bob, in=in, out=out
if keyword_set(in) the out=in+200
end

;pretend sample runs

#1... I want the number 201
IDL>bob,in=1,out=out
IDL>print,out
201

#2...I want the number 200
IDL>bob,in=0,out=out
IDL>print,out
%PRINT:Variable is undefined: OUT.
%Execution halted at: $MAIN$

Also, why does:

IF NOT KEYWORD_SET(keyword) then do-this-stuff

not work?

I've had to do the following:

IF KEYWORD_SET(keyword) then a=a else do-this-stuff

("a=a" acts as some kind of dummy variable thing.)

-Grady Daub

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