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Re: How to see if variable is defined? [message #3404 is a reply to message #3359]

Thu, 26 January 1995 12:28

zawodny
Messages: 121
Registered: August 1992

Senior Member

In article <3g8n7i$ghv@sun2.ruf.uni-freiburg.de> ps@kis.uni-freiburg.de (Peter Suetterlin) writes:
> Mike Schienle (rep2857@sbsun0010.sbrc.hac.com) wrote:
> : IDL> print, var
> : % PRINT: Variable is undefined: VAR.
> : % Execution halted at $MAIN$ (PRINT).
> : IDL> print, size(var)
> : 0 0 1
>
> : The first parameter will be a zero if var is undefined.
>
> !!NO
>
> that's wrong:
> IDL> i=1
> IDL> print,size(i)
> 0 2 1
> IDL>
>
> The *second* parameter has to be zero (exactly s(s(0)+1, which defines
> the type of the variable)

I've noticed that this thread has survived longer than I would
anticipate from the subject. I have not been following it so, this may have
been pointed out already.

I use the following:

if(n_elements(var) eq 0) then print,'Variable is undefined'

This is much easier to remember and is less code than using SIZE.

--
Joseph M. Zawodny (KO4LW) NASA Langley Research Center
Internet: j.m.zawodny@larc.nasa.gov MS-475, Hampton VA, 23681-0001
TCP/IP: ko4lw@ko4lw.ampr.org Packet: ko4lw@n4hog.va.usa.na

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[Message index]

		How to see if variable is defined? By: rfinch on Fri, 20 January 1995 09:43
		Re: How to see if variable is defined? By: zawodny on Thu, 26 January 1995 12:28
		Re: How to see if variable is defined? By: nmw on Thu, 26 January 1995 03:18
		Re: How to see if variable is defined? By: thompson on Fri, 27 January 1995 06:49
		Re: How to see if variable is defined? By: rep2857 on Tue, 24 January 1995 08:22
		Re: How to see if variable is defined? By: ps on Thu, 26 January 1995 09:47
		Re: How to see if variable is defined? By: thompson on Mon, 23 January 1995 07:47

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